Yeah, check CamaroZ28.com and Ebay for the bare LT1 castings. MAKE SURE THEY'RE THE ALUMINUM ONES. If you can, get castings from 92-94 as they're proven to have more metal around the key areas and produce slightly better results.
www.advancedinduction.com is one of the places I mentioned.
For the parts like the rockers, ect.
www.thunderracing.com has very competitive prices and is EXTREMELY reliable to deal with.
Are you saying you've got a guy who is going to do your porting work or who is going to do the installation??