Hello!
If you have the low compression head and use low nitro fuel (5%)
You will have trouble setting the high speed needle (the range the engine works in will be very narrow..it will not go from fourstroking to two-stroking ......just fourtstroke and then...suddenly die!
This is cured by using the high compression head...and do use a Enya 3 glowplug or a OS 8 plug! Idlebar plugs are a thing of the past....and even if this engine is from the early seventies it is constructed to work on ordinary non idlebar glowplugs.

Regards!
Jan K
Sweden