Well I just did this swap in my 65 you will need a new crossmember to start with, Also a flywheel to mate the LS to the 2004r you can get that from TCI you will have to fabricate or purchase http://www.bowtieoverdrives.com/cata...BCAT&CATID=WA5
with out this you will burn out the transmission in a few 100 miles, with that they dont tell you that you need the small small cam throttle body as well. other than that a lock up switch for the converter as well! other than that easy swap!
Never mind I didn't see your going carb route! just make sure you set the TV cable correct!