Good Initial Timing and Too much Total Timing Problem. Seeking guidance to minimize total timing. 1969 Swinger 340 4 Gear

I'd pull the distributor and see what type of advance mechanism it has. Sorry.
The advance is way too quick and too much, even without vacuum advance.
If you have no choice, try running it at 8*BTDC 700 - 750 rpm, and don't use the vacuum advance. That will get you by until you can see if it can be adjusted and recurved, or you can get a different distributor.