GEORGE GERSHWIN, at a no doubt impetuous moment when flushed with the full heat of composing his prodigal but uneven masterpiece, "Porgy and Bess," declared to the world: "The production will be a serous attempt to put into operatic form a purely American theme. If I am successful it will resemble a combination of the drama of 'Carmen' and the beauty of 'Meistersinger,' if you imagine that." Self-effacement never was high on Gershwin's list of Problems.

He was asking for trouble with that sort of public statement. And on Oct. 10, 1935, when "Porgy" opened, the reviewers fell all over each other in pronouncing that "Porgy" was not "Meistersinger" (which it certainly isn't). In the process, the work's manifold merits got sold short. Not everybody missed the point, however; Serge Koussevitzky, the Boston Symphony's conductor and the preeminent musical patron of his time, recognized in "Porgy" a great advance in American opera."

This shaky start helps to explain why until recently what is one of the century's most notable theater pieces lived a curious existence. The original production lasted only 124 performances.In addition, Gershwin had unwisely consented to major cuts (among them the piano music at the begining, Porgy's Moussorgsky-like "Buszard Song" - one of the work's high points - and the haunting trio to "Where's My Bess?") and most of these cuts were honored in subsequent revivals for almost four decades, as well as in the film version.

We were getting only part of "Porgy" - even in the memorable Leontyne Price-William Warfield revival of the 1950s. And to my knowledge this inequity was not corrected until last year, when the Houston Grand Opera and Sherwin M. Goldman staged an uncut production of "Porgy" that stopped at Wolf Trap on its way to Broadway (where it recently won a Tony) and is returning here Wednesday for a welcome three-week run at the Kennedy Center.

Coincidentally with Houston's version, London Records issued last year a complete recording with the Cleveland Orchestra, no less, under Lorin Maazel (OSA 13116, three records). And now comes a rival version with the Houston cast, on RCA (ARL 3-2109, three records).

Comparing performances of the at-long-last-complete "Porgy" (it's almost exactly three hours long, with Maazel three minutes the shorter) allays any lingering doubts about whether this work by a man from Tin Pan Alley who called it a "folk opera" is indeed of operatic stature (a subject about which critics have wasted much time fretting). In fact, Gershwin's presumptuous analogy to "Carmen" is, in some ways, not so inapt. The central stories are similar - poverty, ignorance, passion, promiscuity (and in the case of "Porgy" drugs and racial discrimination) leading to jealousy and finally to murder. Both have extended dialogue (in "Porgy" it is sung and in "Carmen" some productions sing it and others don't). Both integrate the chorus into the action, intensifying the pathos. Both are propelled musically by an impending sense of doom, and both Gershwin and Bizet are melodists of the first order.

If "Carmen" is though, in the last analysis the stronger work I think it primarily is because Bizet's music touches a wider range of mood. Gershwin at age 36 was already the master of lyrical love ("Bess, You Is My Woman Now" stands comparison with anybody's tune), the sardonic patter song ("It Ain't Necessarily So"), the lullaby ("Summertime") and so on. His orchestral atmospherics are often memorable - listen to the evocation of dawn at the waterfront that starts Act 2, Scene 3, or to the ethereal beginning of Act 3, the calm after the storm in which Clara and Jake have perished. As a lyric composer, Gershwin had reached full maturity. It is when things get menacing that "Porgy" is less effective. There is something almost humdrum about the orchestral interlude during which Porgy kills the villain, Crown; by constrast, at just such a moment, when Don Jose stabs Carmen, Bizet is at his most gripping.

But, as an opera composer, Gershwin was just getting started; as Leonard Bernstein has said, "With 'Porgy' you suddenly realize that Gershwin was a great, great theater composer." Who can doubt that he had a "Carmen" in him? And listening to these performances convinces one all the more that Gershwin's death at 38, less than two years after "Porgy" was one of the greatest losses to posterity music has suffered in this century.

The London version has great sonic ambience and it's a joy to hear an orchestra of Cleveland's exalted rank in this music (they certainly resolve any doubts one might have about Gershwin's skill as a orchestrator). But "Porgy" is above all a singers' opera, and RCA's cast has the edge in almost every principal role. The Bess, Clamma Dale, who unfortunately won't be singing at the Kennedy Center, is absolutely first-rate. The norm in this role, of course, is Leontyne Price, who can be heard with William Warfield as Porgy on a record of excerpts made about 10 years after the 1952 revival that made stars of them both (RCA LSC 2679). Admittedly Dale's voice lacks the amplitude of Price's midrange and neither she nor anybody else can match the heady resonance of Price's high notes. But Dale's high voice is unusually radiant and the evenness of the whole range is striking. And her diction, attention to dynamics and rhythmic care often actually outmatch Price. Yet there is something about Price's passionate abandon that Dale doesn't equal. Leona Mitchell, on London, is splendid, but her voice is lighter and dryer.

On the complete sets, the Porgys are more evenly matched. But if I have to choose, RCA's Donnie Ray Albert (he will sing at the Center) has a mellower hue that fits the part better. Also, London's Willard White showed strain several times on high notes. Both men have exemplary diction - a major factor in this long and strenuous role ton the stage played white kneeling).

Larry Marshall's portrayals on RCA of Catfish Row's dope peddler. Sporting Life, is sly and rasping. But the male character in which RCA most decisively scores on London is Andrew Smith's Crown. His macho elan makes London's McHenry Boatright seem especially threadbare. (Marshall and Smith will be at the Center).

Of course, the respect in which London most consistently outpoints RCA is among individual soloists in the orchestra: The solo cello introduction to "Bess, You Is My Woman Now" has pitch problems on RCA, whereas the Cleveland Orchestra's first cellist plays it to perfection. John DeMain conducts on RCA; his is often the more inflected and rhetorical of the two interpretations, and I must say I rather like it that way.

It should be noted that there is a bargain "Porgy" on Odyssey (32360018E) that is substantially complete. Conducted by that dedicated scholar of and advocate for the musical comedy, Lehman Engel, the performance was a valuable achievement in its day: for years, the recording was the closest thing to a complete "Porgy" that we had. But in all respects but price, it has been superseded.

Finally, what do we recommend to the listener who heeded our advice last year and went out and played a considerable sum for the London "Porgy," only to read now that we think an even better version has been issued? For the incidental listener, the quite splendid London performance should suffice. But for music lovers with a passion for "Porgy," RCA's set justifies the extra expense. At its best, it's enchanting.