Yanking hard at idle???

DSMRossi said
So what I’m finding is it wants to be right at 22 degrees at idle with the vac advance plugged.

With that compression and cam my guess is the engine will be happy with less than 22* with a richer idle mix. If will also make more power at idle - so less drop in rpm when placed into gear. Just go a little at a time. Open up the idle mix screws a bit, then lower timing a couple degrees. Bigger timing leads are needed when the burns are slow. They're slow with lower compression, slow with lots of exhaust dilution, slower with lean mixtures. You may end up with an engine happy (in gear) with timing in the 16-20* range if you keep fiddling with it.
When the engine is cold - and no choke or fast idle - you may have to two foot it for a bit, especially in the winter.

Once I hook up the vacuum advance, revs start bouncing. In order to make them stable, I have to retard the timing to flatten it out.

Does your carb have a timed vacuum port? When you are ready to hook up vacuum advance, use that. If it (timed vacuum port) is seeing vacuum at idle, the throttles blades are too far open at idle.