Building a 430 from a '69 Wildcat. The car has been in my family its whole life. I was hoping to use the original heads but the machine shop found numerous cracks in both heads. Fortunately, I have many 455 motors and lots of spare heads lying around. Today, I went through my head pile and pulled out a set of 1970 heads and a set of 1973 heads. The '73 heads were produced earlier in the run so they only have the single water hole which will match up to the '69 block fine. The '73 heads are ready to go to the machine shop. The '70 heads have several broken exhaust studs and will require at lot more work on my part or a lot more money at the machine shop in order to remove the broken studs. Here are my questions. 1) Is there much power difference between the two sets of heads? 2) The rockers were oiled differently on the '69 models as compared to the '70 and later models. Is this ok as long as I use push rods with the hole in the center and the later 1970 or later rocker arms? 3) Is there anything else I am not thinking about? Thanks!