Hi, this is my 1st post and I'm sure this question has been beaten into the ground, but I have to ask. I recently picked up a chevy big block, 3969854 casting number, and a set of heads 3999241. I quickly ran a caliper, did not have a mike with me, and got 4.114 on the top of the cylinders, so I'm guessing its the 396 with wear??? Ok dont roll yer eyes , I'm new to this remember. Anyway wanna build up a small light ride for my local strip, and utilize weight to hp ratio to the max. Im thinking opel gt. Question is: will the heads I have hold up to a 450-475hp build without alot of carressing or is there a better pair to start with? Production type. AND.. can someone tell me what parts off the 427 and 454 will interchange to my favor. Ive heard people on here talking about strokin the 402. How is this accomplished??? Thanks guys for readin me.