Well Bluejimmy basically basically said it. As long as it starts hot & cold, I wouldn't TOO much. Well exceot the vacuum advance. However, I would at least throw some timing tape on it. Coat it with a little clear nail polish, around the edges and it should last a little longer. This way you can everything correct and can use for future reference. You might have to fool it with again for the planned head swap and header install.
That's why I asked about the distributor. Like how did you set up the vacuum advance and what springs were tried first? Here's another link that should help you out, one way or the other. They do a good jog explaining, instead of someone else retyping it. Damon doesn't frequent here, but Mike does.
http://www.73-87.com/7387garage/drivetrain/hei.htm