I tore the motor apart last night and was treated lovely collection of various shapes and sizes of aluminum in every conceivable nook and cranny, some even made it upstream past the reeds into the carb.
Before I took it apart i put the head back on and did some measurements. The squish band was just over 2mm and the points were opening at 18deg.
I have a mvt cdi I hadn't put on yet, think with the timing curve this might be easier to avoid? I will probably put it on when I get everything back together.
Also I'll either weld up that hole on the head or run a stock head next time around. A 2mm squish is pretty safe if i remember correctly right.