Chris,
I'm having a distributor set up by Dave Ray.
Do you have the dollowing info available?
Out of gear idle speed:
Intake manifold vacuum at idle:
Initial timing with vacuum advance disconnected:

I'm running the 280/288 also. That's why I'm asking. Thanks

Gary,I run 18* base @ 800 rpms in gear/900 rpms in neutral/park,and 38* total by 3,000 rpms..I do not run any vacuum advance.

Forgot to add that I have about 15" vacuum at about 800-900 rpms