Bandit,
A couple of things. First, dropping a BBC in there will make it no longer a Trans Am, both in the engine bay AND in performance. BBC is significantly heavier than any of the original engines those cars came with. The end result is a nose-heavy, plowin' bitch, no longer worthy of the name "Trans Am".
Also, we have first-hand experience with those 502 horse 502s. As with any other Chevrolet production engine (that's all those are, by the way...), the first thing you must do, if you expect it to make power AND live, is to disassemble and blueprint it. We know of at least two that started out as $7K craters, and ended up being over $14K by the time all the corrections were made, and parts changed to actually achieve the power level claimed.
As with anything else, you get what you pay for. A crate motor is easy and convenient. You will note the absence of the words "good" and "powerful" in there... Ya, ya... I know. Many people love their craters. Compared to what?
Everyone on this board already knows what's coming next... Build a Pontiac and beat up on the others! For the very same $7,500 you would spend buying and shipping the crater, you could have about 50 more HP, and nearly 100 lb. ft. more torque, by using a 461 Pontiac. Bump it up another grand, and you get aluminum heads and 600-plus HP.
The best part of using the Pontiac, is THAT is what the car was designed for. It fits, and the weight gives it the best of all possible worlds, when it comes to "balance".
Of course, putting the Chevy in it would assure no Pontiac guy or gal would give you the time of day, either at a show OR the track... We're funny about that.. Kinda like what you get from Chevy guys when they see a 400 Pontiac in Corvette... It's BEEN DONE!
It IS possible to extract a ton of power from the Olds. It's not nearly as practical as either the Chevy or the Pontiac, nor will it live nearly as long. But, as before, it HAS been done!
Jim