Iam building another chev small block and want to install comp cams roller cam in my 1993 gmc truck. Its basically a L31 block 9.5 to 1 comp with a tbi gmpp intake and bored out 46mm throttel body with 18 psi fuel pressure. The cam i want to install is a 08-409-8 . duration @ 0.050th is in 206 exhaust 210 valve lift intake 0.458 exhaust 0.458 ls 111 When i tried to check it out on cam quest it did not come up , the cam that cam quest showed is 08-408-8 duration @ 0.050th is in 206 exhaust 212 valve lift intake 0.480 exhaust 0.487 ls 110. Which is the best cam for me to use? Iam using 062 vortex heads do i need to change valve springs with these cams ? Not to confuse matters but another comp cam i was looking at was 08-300-8 which might have to much lift on the exhaust 0.480 @ 50th with my 062 vortex heads, but it is more in the power band i will be running. Would I have to have these heads machined with the 08-300-8 cam ?