If you buy a new engine, and get the correct bearings, you can use the long shaft that comes on the engine. It has a reverse thread bolt usually at the end already. Then you just need the clutchnut from a gt2 and you can end your frustration.

You can tap out your clutch nut shaft, but the problem is the engine spins counter clockwise and it will turn off your screw when you run it.

CR used to make a revers threaded clutch nut but they went out of business.