You can also read my thread.http://www.ls1truck.com/forums/lsx-t...zer-build.html
I swapped out a 92 TBI 350 for a 2005 323 (5.3l)
TBI means Throttle body intake, they basically replaced the carb jets with two fuel injectors. TBI is crap in short. So EFI or nothing to answer your question.
Read my thread, This is probably close to what you will be doing if you decide to go with a swap.
Btw, welcome to the site! Feel free to PM me any questions you might have! Cheers!