Been busy settling into a new house, but I ran it to 6k on the street yesterday without any sync loss events.
My first attempt was using a copper tinned shielding sleeve(grounded) to help insulate the sensor wiring from the nearby alternator. That didn’t help. Next I dug into the harness and changed my crank pickup sensor from 5v ref to a 12v power source. That helped a little, but still losing sync. Finally, I dropped the sensor gap from 1.15mm to .80mm(.031”) and that seems to have done the trick. Still need to drive it a little, but I’m hopeful. I may drop the gap even more as suggested. If this doesn’t work out I’ll build a new crank sensor bracket away from the alternator. If I have to dig into the harness much more it’s going to turn into a complete re-wire and real megasquirt ECU.