If it all lines up, I'd make up some shear pins from brass and try it. I've run propellers that were designed for clutches with just brass shear pins without trouble, but they were 6 hp or less. just make sure the propeller won't fall off if a pin shears.
Bryan - I've got that parts diagram but the shaft I have is not splined. So I am confused. I've also been corresponding with Joe Poole. Is there a way I can send a pic and if you had a pic of a KG7 propshaft with hardware that would be great. The diagram is not very sharp in the parts manual. I see parts that are clearly spined but the prop shaft doesn't appear to be. isn't. Also - it shows a bunch of parts number for clutch assembly (52-24488) but not for the KE7.