Back in Louisiana, there would have been six tender pigs roasting up nice and easy on a spit. The time would be late afternoon, the dress shirtsleeves and the talk, who's got a shot at governor. Lots of kids around, too.

But the "Louisiana Buffet" fund-raiser last night for Rep. Gillis Long (D-La.) lost a little in moving closer to the Mason-Dixon Line. Politicians instead of pigs. Car-parkers instead of kids. And mink, lots of it.

"Honey, it's cold." said a mink-wrapped Charlotte Gran, wife of a man who makes scads of money selling ships in Texas. "We live in Houston and it's hot as hell down there."

The $250-a-head fund-raiser was held at the rambling new Foxhall Road home of Eunice and Sargent Shriver. It comes with a tennis court, swimming pool and pond of ducks and algae. And yes, it was cold. Especially on the terrace, where almost 500 "Gillis goupies," as one guest put it, huddled together for warmth in the mid-October chill.

The evening's nip caused House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) to shake hands with more than the usual gusto.

"Oh, beautiful woman," O'Neill cried, grabbing a hand that belonged to Peg Brown, wife of the legislative director for the International Union of Operating Engineers. "A woman with warm hands. It's the first one I've met tonight."

O'Neill had arrived late, but not late enough to miss the bulk of the crowd that rapidly ate every shrimp remoulade and crawfish etoufee in sight. The number of people, O'Neill told Shriver as he greeted guests in the still rugless dining room, was impressive.

"Yeah," O'Neill said, "you got 'em from all over. I just met somebody out there from Indiana, and it wasn't John Brademas." O'Neill was referring to the Democratic representative from South Bend who seldom, if ever, misses a good party.

Aside from shop talk, which was oil, airlines and even shrimp from the lobbyists in abundance, everybody talked architecture. Shriver house architecture. After all, it once belonged to the late Nelson A. Rockefeller and reportedly cost $750,000.

"They were smart to buy this," said Ann Braverman, a long-time friend of Long's.

"Wonder if they get the lake?" mused her husband, Marvin.

They do. And 30 rooms, too.

"We're not worried about rattling around at all, thank you," said Shriver, when presented with the Eunice-and-Sargent-rattling-around-in-a-big empty-house-with-only-two-kids-of-five-still-home theory.

And then, of course, there was the real matter at hand: money. Assuming 500 paying guests, the middle-of-the-road Louisiana Democrat who's not sure about backing Carter made $125,000 last night. He already has $140,000 in his war chest, and no visible opponent.

But, said Wayne Thevenot, a Washington lobby consultant, "Gillis has a very big and complicated district with five major television markets. It's a very expensive market to campaign in."

Added Thevenot: "And a lot of these people see Gillis as a comer. They anticipate he's going to be in the leadership one of these days."