That's good that the distributor is dialed in already. Just give it a check w/a dial back timing light (or whip up a temporary timing tape) to double check it. If the damper is a stock part, it's a good idea to double check TDC to be sure the outer ring hasn't moved. You can mark it w/a line to keep an eye on it.
One thing more- you can
use a vacuum advance, and I recommend you do so. The caveat on this is twofold:
• Use ported
• Use a Crane p/n 99619-1
limiter plate to keep the added advance to about 10-12 degrees (or make one)