Why are we on this path without checking the basics? Are you running on one cylinder?
Pull each spark plug wire one at a time and see if performance changes. If it doesn't, then the cylinder isn't contributing. Are you misfiring, firing both cylinders but one out of phase? Put a timing light on each cylinder. Make your own marks if you have to. You should see nice crisp marks, no intermittent chatter or variations. If you have good spark, jumping a 3/8" air gap, you can still have a crappy spark plug killing a cylinder.
Check compression with another gauge. The lower the reading the more percentage error gauge-to-gauge. I've got '65 seems to be running well at 85 psi.
J