Thanks guys! Yea I'm getting my specs together,but I think I'm going with the 331 stroke .I hear it lasts longer than the 347?I want to go with the 12,5:1 comp. with the 58cc heads and a solid roller cam.I've been running a c4 behind a 302 with a bigger edlbrock cam and a 750 holley and a 100 shot of nos.It was an old motor that sat in the pasture for 12 years.Its blowin by one of the intake valves now.So its time for a rebuild.Is there some kind of marking in the block to show if its a mexican block and are they supposed to be better?