Out here in Kalifornia, we are mandated to use TBI (if the car came with it) so we are planning a buildup on my buddy's 305 once the 331 goes in. He wants to keep the original engine and we have to keep the TBI, so that is what we have to work with. His 1991 305 is a factory roller motor, so I wanted to ask, how much lift can we get away with on the 305 TBI heads???? I found quite a few spring sets that give a higher installed height, but I wanted to ask you guru's before we order ANYTHING. The cam I am looking at is a Comp XFI Roller that is designed for the '87 up factory roller applications, buut its .560"/.555" lift seems like more than the stock retainer to guide clearance will allow. We will likely do some tuning when this 305 is donw, so we have a little freedom on the cam. Any advice from Chevy Guru's would be welcome!!!!!