I hear u i drilled my heads and my motor was done 10 years ago and I still beat on it with no problems it just need to be fresh end up where it sets so muchthanks for the info I'm pretty sure Mines is going to be in the 12 second range with a slick and a 390 rear endand as far as boring the 400 out to those dimensions its not a problem my grandad had a 412 and ran it for years no problemwith the overheating problem it's not the motors it's the ownerswho forget to drill steam holes in the head when they swap them out or leave the radiator clogged