As long as it isn't electric start it'll fit ... but once again the auto clutch is on the crank and mightn't handle the quicker rev up of the IRK ... What happens is that they start to balloon outwards ... Die cast metal can't handle higher crank rpms ... it starts to break up after a while ...
Start in gear engines have the clutch on the tranny where it does around 1/3 rd of the revs of the crankshaft ...