OK, I've finished off my drivetrain, at least I think. I used a die sander to take about 1/4" off each drive shaft. This puts the WSN sprocket to the correct depth. I hollowed out the WSN gearbox cover and reattached it with the stock hardware. To attach the drive sprocket I drilled out and tapped the HL driveshaft with a 10-32 thread. I took the WSN drive pin and cut it down in length and threaded it with a corresponding 10-32 thread. A before and after pic of the pin is shown below. Now I can 'screw' on the drive sprocket. If needed I will treat with Loc-Tite but I'll do that later seems pretty robust right now.