Super Bowl 13 provides an appropriate ending to the 1978 NFL season.

This past year was the toughest in quite awhile for many handicappers, and the championship game in Miami Sunday shapes up as the more difficult to pick, against the spread, than the 12 that preceded it.

The Las Vegas number is 3 1/2, from 3 or, in a few instances, an opening quotation of 2 1/2. Pittsburgh, the AFC king, is favored over Dallas' NFC winners. The victor becomes the first three-time Super Duper. The loser goes home with the satisfaction of knowing it belonged in the game. For one of the few times in the NFL's history the best team in each conference "got there."

The fact that Pittsburgh is favored by more than a field goal is a little surprising in that, less than a month ago, when "Head Linesman" Bob Martin was asked to project the spread on a Pittsburgh-Dallas matchup he tabbed Dallas a 4-point favorite.

Much has happened to turn Martin's projection around. The Steelers have been extremely impressive in dismantling Denver and Houston before hometown fans in Three Rivers Stadium. The Cowboys meanwhile, were flat in the first half against Atlanta and did not exactly overwhelm Los Angeles despite a final 28-0 count. The score was 0-0 at halftme.

And now it all comes down to the Pittsburgh offensive line aganst the Dallas defensive line. That is what Super Bowl 13 is all about. The other line's matchup is predictable. Dallas will not be able to run with any regularity on Pittsburgh. Roger Staubach will, accordingly, be under pressure much of the time when he tries to pass.

The Cowboys, in short, are not going to have a big day putting points on the board unless their defense creates the same sort of turnovers that it did in Los Angeles.

This is possible, but Terry Bradshaw is not to be confused with Pat Haden. The Steeler receivers and its running game are far superior to those of the Rams.

One matchup, in particular, would scare me if I were a Dallas fan. It involves Binnie Barnes, on the left corner, with primary responsbility for covering Lynn Swann. Barnes gets help when ever possible from Charlie Waters when Swann comes across the middle, deep, as he loves to do.

I believe Swann is going to have an enjoyable afternoon against Barnes, unless Dallas adjusts its pass coverage so sharply as to give Bradshaw an open invitiation to throw to John Stallworth or tight end Randy Grossman.

The single most significant development to look for early in Super Bowl 13 will be whether Franco Harris can run on Ed (Too Tall) Jones, Larry Cole, Randy White and Harvey Martin. If Harris, operating behind Pittsburgh's excellent offensive line, is able to generate a respectable amount of rushing yardage, Dallas is doomed. There is no way the Cowboys will be able to stop Pittsburgh's aerial game unless, first, they shut down Harris.

I doubt that Dallas, for all its defensive flexibility, can handle Pittsburgh's balance on offense. The Steelers are going to score 21 or more points. I make the final tally 24-17, Pittsburgh.

The risk is a mythical $250, giving the 3 1/2 points.

This is hardly a tap-out situation. There is no Craig Morton to kick around, as there was in Super Bowl 12. The spread is an invitation to go with Dallas, not Pittsburgh, but the basic matchups dictate a Steeler selection.

If I win, the net mythical profit for the year will have been $705. If Pittsburgh loses, or fails to cover, the profit will have been$180.

Either way, it's nothing to shout about... while certainly nothing to be ashamed of. It will mark five straight seasons that "Playing Football" finished ahead of the game. The net mythical profit will have been somewhere between $27,000 and $28,000 for the five years.

I never promised you a rose garden, or a swimming pool, every season. But I hope it's been fun, beating the mythical bookmaker again.

See you in September.