Manifold Vacuum Experiment
I'll try to get it right this time.
After turning the adjustment screw full clockwise Idle timing increased to 40 deg. and idle time w/out vac remained at 20 deg. 20 deg. initial is where you had it set prior to replacing
the vac. adv. So the assumption is the mechanical advance curve hasn't changed.
Your observations were that the engine idles cleaner by a good bit and the engine has more balls at part throttle pulling up inclines.
Separating the two observed results. First the cleaner idle. I think this can be attributed to using manifold vac.
The second result, "more balls at part throttle", can be attributed to either the full clockwise adjustment (previous diaphram was set to mid travel) or a working diaphragm in the new vacuum adv. or a combination of the two. This second result would have still been realized even if the vac adv. was connected to ported vac. only.
One last caveat, the Idle fuel restrictor was also changed. If this was changed and test diven before the vac advance change then the back to back results should be valid. If not we'll wait to hear back after the restrictor is changed back to original to see if it changes results one or two.
Looks like your combination benefited from the changes you made so far.
Good job testing and tuning. Thank you for sharing.