Hey, Jon, how ya been?

Are you running the stock fuel pump with a pressure reducer?

Harbor Freight sells a Mi-T-Vac system for cheap that you can apply vacuum and pressure to systems (and bleed the heck out of brakes). It's marked as a Harbor Freight/off brand, but it's the real deal in the box, instructions and all. I'm glad I bought mine. You can check vac advance and other dashpots, etc.

Have you checked the distributor to verify centrifugal advance? Recheck wiring around the dizzy and look at the running engine in the dark to easily see any arcing.

Check for vacuum leaks with an unlit propane torch. Increased rpm's means you have a leak right where the end of the torch is.

Just some basic stuff I could remember, maybe too basic, but what the hey.

John B.