Yeah I wrestled with a totally stock motor versus adding a few modifications. In the end, the speed bug got me and I decided to go with a cam that has a higher lift, 1:65 rockers, a different intake, and carb. I wanted to make sure the engine could breathe once I put better heads on. I never did get better heads. Right now I have the factory 6X heads that were re-done. I did go 10 over too, to clean things up. Beyond that, it’s a standard rebuilt 455.

Another thing is that I'm using the timing cover from my 68 350, to keep more of an authentic look. I'm not sure if that would cause any issues.

So the 3 core won't work for the 455? It worked for my 350 with air conditioning, so I thought it would work for a 455 without air conditioning. Could I take it to radiator shop to have the flow tested to see if it's flowing enough? Or is there just a general rule that 455s are too hot for a 3 core?