If I did my math right, puts exhaust lift at 612, is this too much for an LT1? I have an opportunity to get a set.

 

It all depends on what valve springs you use, and how high you are willing to rev your motor, and if your valvetrain will take whatever rpm you will be throwing at it.

 

Kim Barr built my heads and said the spring is good to 650 lift, not sure the exact specs on it though. They are dual coil springs. I was more worried about clearances, if I would have valve collision and bend them..

 

I have a cc306 w/1.6's, I have always heard that 1.7's on a lt1 is pushing it but i am not 100% sure?
Might want to run it past a shop like speed inc that deals with alot of lt1's, the 1.6's on my z28 are fine.