I know there are lots of threads about this, I'm relatively new to cars but I'm wondering would any 350 work? Like could I just buy any 350 off the chevy performance crate engines?

 

they will all fit a thirdgen

 

"fit" used loosely. Get a 2pc rms engine and try to put it in an 86 or newer thirdgen, and the flywheel wont bolt on. Grab an enigine with a driver's dipstick and thirdgen maifolds wont bolt on. Get pre-87 heads and an 87-up intake won't just bolt on. Get a Vortec engine the intake won;t even come close.

That's why there are so many threads. A person could take the time to make a comprehensive guide, an in depth thread, customized replies, but no one would read them anyway when it's easier to just post and wait for an answer.