Ok fellas heres the deal i researched this but havent found a definate answer, i just bought another truck a 96 12v to play in the hot street class with anyways on my other 12v i had the o-rings cut in the block which was expensive and have had no problems with it, on this truck a local machine shop said he has been cutting the o-rings in the head, my question is i see not much real difference with this but thats where you come in which is better i will be running twins at about 75psi, thanks for the help.

 

O-rings are generally cut into the head. I don't think it would make a difference where they are put.