Using the picture of the nut above, you can also drill on the face of the nut, as close to the shaft as possible, and parallel to it. This usually takes a bit weight off the output shaft threads. Usefull if you no got Dremel.
As the R1 stem is alloy, I'd go with a B12 stem. Even a B6 one might do you? Take it along to your local engineering company, and they should press the two stems out, and re-fit the Bandit one for beer money!
Machine Mart are selling a Clarke one for £70 at the minute. I used it on the B12 clutch centre. Not locked off, no bits of wood in the wheel. Unbelievable! Well worth the money.