I honestly don't know if it's that simple. In previous posts in the thread they say it is. I do know for a fact that 302 heads are usually 69ccs, that's why I swapped them on my '69 Barracuda (318, 69cc heads). I also know that my factory 318 had 9.1:1 CR. What I was saying is that if those heads are 57cc...that's pretty good for a small block head. As far as the water ports, I was saying that all you should have to do is block them off and then use them but I don't know if there are any other issues besides the water jacket?? Maybe someone else will know>>