72 360 first start question

like I said, i have put a timing light on it and it's not even close. I get the whole thing about setting the rotor to any point as long as the firing orders starts at that point. But.... It's a brand new engine so why wouldn't I just start it #1 like it's supposed to be? I have the rotor set pointing to #1 at TDC and the firing order is correct running clockwise. It'll run and sounds good with the throttle pegged. when I let off it dies. I've advanced and retarded as much as possible and it'll only really run when I start it with the #1 on the cap lined up with the rotor pointing at #1 cylinder at TDC which is how it should be. It's a weird one. Rapid Robert, how do I check the rockover exactly?

thanks