Did you bring the #1 piston to TDC on the compression stroke before installing the distributor? Did the mark on the balancer line up with 0 degrees on the timing tab? Did the rotor point toward a distributor cap tower, and does the wire on that tower connect to #1 cylinder? When installing the distributor, did you account for the helix of the distributor gears and start out with the rotor pointing about 3/4 inch clockwise of where you wanted to end up?
These four questions are to determine whether you are actually "advancing it pretty far". It may just be that the distributor is a tooth off.
Is the starter stock or mini, used or rebuilt, and how about the solenoid?
The starter issue is generally heat + timing. Sort out the timing first, then recheck the starter. Yes, headers can heat up a marginal starter very quickly. You may want to consider a heat shield.
Vikki 1969 Goldenrod Yellow / black 400 convertible numbers matching
