Still haven't figured out the idle issue...

OP, did you mean .012" and .022" on the lash? (You listed .12 and .22 so I assume that is a mistake LOL).

Well, my /6 idles good at 5 degrees BTDC initial ignition timing BUT that is a 1 BBL Holley 1920. not a 390 cfm 4 BBL. Yes, add 5 degrees of ignition timing and see what happens; if it improves this problem then work over the ignition timing setup.

Also, check:
- Float level in the carb... triple-check it! This is critical to all phases of carb operation.
- The secondary stop screw and adjust it so that the bottom edge of the transition slots in the secondaries are just BARELY visible. Then reset up the carb and try again. This secondary stop screw setting is important to make the idle-to-cruise transition work right. It may take several iterations to optimize this so work this issue thoroughly.

While you are doing all of this, it can be useful to put a vacuum gauge on the manifold vacuum port and monitor it while the car acts up; knowing the vacuum levels when things act up can be a useful tool for knowing what it likely going on.