Harms Rebuilt '71 Thermoquad - Wondering Idle, Stalls when Put in Gear

Something not right here, getting drip fed info....
Now you say the Edel wandered at idle.
And the engine is 'bone' stock?
Stock engines will have 16-19" of vac at idle, not 10-11".
A stock engine should idle at 5-600 rpm, not 900....
Since this problem has occurred with TWO carbs, & from what you have done so far, I suspect the engine has had a larger cam fitted. That would also explain the 16* init timing [ which is good, not a problem ].
The high idle rpm could be activating the centri curve in the dist, especially if the springs are stretched. This could explain the varying rpm & needs to be fixed first. Check by monitoring the ign timing with a timing light.
One last thing to try: initial timing is at 16*. Loosen dist, engine idling, turn dist slowly CCW; keep going until rpm stops increasing & THEN see what the timing is.
I suggest you try the above & report back.