No there wouldn't. The '79 version (which is a '78 in disguise) is rarer as it was the last year. Chances are no one will split out a '79 400 for anything :).
Dennis: There are TONS of 403 equipped Trans Ams. I have encountered several over the years from 77-79 when they were made.
Not just high alt and California----many folks couldn't afford the 400 and got the 403 or chose the 301 as a credit engine.
I have seen this on certain cars I've looked at over the years. The person must have checked off all the options and was so tapped out by the time the salesman said, "how about the $90 400 engine" that someone must have said, "Nah, I'll pass, I have the bigger 403 anyhow!!"
I looked at one car where the guy was the original owner (it was a 403) and he told me, "Yea, I told the salesman I wanted the biggest motor I could get, because that was the fastest".
LOL. Joe--ASE Certified Parts Specialist & 10th Ann.Club Tech Director '80 Carousel Red Turbo T/A, 27k orig. '79 "Y89" 400/4 speed 10th Ann. T/A, 57k orig '84 Olds 88 Royale Bgm 2 dr, 307 "Rocket" (lol), 143k and still going.... '91 S10 Blazer 4.3Z