1980 3.0 6k rpm stutter

[WigglyWorm]

Hello. I have a 1980 3.0 used mainly for DE’s and spirited driving. It ran awesome but had poor compression in one cylinder, so I tore it apart to fix it. Once back together it ran pretty bad over 3k rpm. After much trouble shooting and many beers the problem appeared to be the vacuum retard diaphragm was completely blown and the pieces were affecting the vacuum advance. I shook out all the pieces I could and the vacuum advance started working again. I set the timing to 32° and CO to 4.5% (Thanks Mr. Walker!). The idle was a little high (no vacuum retard?) but I was able to adjust it down to ~950 rpm using the idle adjustment screw. The car runs awesome until about 6k rpm, where it begins to stutter a little bit. Now I am confused on what to do next. Should I back down the advance a little bit? When I timed it, I was getting full advance around 4k rpm.

Is vacuum retard needed?
About what rpm should I get full advance?
Should/could I remove the vacuum advance/retard and switch to mechanical advance like the guys with carb conversions do?
Anything else I should be looking at? Plug wires, cap and plugs are all pretty new.

TIA,
WW