Progress!
I have some air bleed blanks on the way (Tues.) so I popped in the only small PMAB I had on hand, .026, and dropped the PMJ to 73.
Now it runs quite a bit leaner - cruise is up to 13.5 at 15" Hg, 3000 rpm (in 3rd gear). The .059 PVCR probably could be a bit bigger but I'll save that for later.
Don't have time today to go out to the highway and try it at 60 in 4th. But if the vacuum and the rpm are the same, the load should be the same (I hope).
AFR gauge wanders less too.

But the flat spot off-idle is a little worse now - guess I misdiagnosed the symptoms and there was significantly more contribution from the mains even below 2000 rpm than I thought. I may need to richen the idle just a bit (it's on the lean edge right now) and that's quicker and easier than pulling the bowls yet again.
Also I haven't even looked at the pump cam yet (.035 squirters, pink cam). Anyway it's not bad and I can live with it.

I also need to get out on the highway and make sure I'm not too rich at higher rpm's on the primaries.
Then I can try (very) brief blasts on the secondaries (currently .030 SMAB, #86 SMJ).