just rebuilt runs bad

That's right, just make sure you are watching when the valves just start to open. It might be hard to see when the valves are just closed. If you had a dial indicator to read when the valve moves it would be better but if you watch closely you should be able to get pretty close.

Did you ever get a better explanation why the original timing set wouldn't work?

No, I need to do that. I feel that I understand enough now to be able to follow the explanation. Thanks.