Ok went back to it this afternoon and surprise surprise wouldn't start or run properly.
I can get it started but fails to idle by itself but will run if I hold the throttle open although there does appear to be some sporadic misfiring.
The dizzy cap appears to be a terrible fit not sure if thats the norm but even with the locating lug on the cap in place on the head there is still about 10 degrees rotation adv/retard and it can move about quite a bit.
Going to get a new dizzy from halfrauds see if that helps...