Old hat...

Vacuum: Yes. As noted, 11º in the can, attached to ported vacuum. I've been back and forth between ported, manifold and no vacuum at all to no effective resolution. I should look into a lower sprung canisters maybe. Vacuum at idle is close to squat and unstable...the 'dither' effect of that makes for a timing mess when using manifold vacuum. OR...go back to a no-can all-mech setup I used on my 292º purple shaft engine. I'm getting hung up on trying to make vacuum work in my current 'less' engine; that is maybe a mistake.

Re: 20º initial. What is your vacuum at idle..and what is your idle speed? 5000'el. makes for a huge adjustment factor for sure. I grew up at 4100', always enjoyed a trip to the valley where engines RAN!