Drive system

I've been looking at how to connect the motor and gearbox so that I can get the adapter plate made ready to bolt it all in to the frame soon.
I've modeled the gearbox, motor, curtis controller and gearbox mount so far, I'll model the rest of the frame and main parts just to get an idea of how it fits together as it seem like a good opportunity to draw it up and when I was looking into doing this I couldn't find any information or dimensions for any of the Smart components. The gearbox is representative and the casting shape not accurate, although the holes and shafts positions should be close enough to make sure things line up.

This is the mount plate, Dia 290mm and 70mm thick, this thickness is needed to move the motor far enough away to prevent the motor shaft and gearbox spline clashing. I'm hoping to track down a clutch spline cheaply but the Smart clutch is a whole assembly which I don't need. The cutout is for the drive shaft, so the motor couldn't be much larger diameter.

Section of the mating parts, just need to sort out a coupling but I think this will be a taper lock plate bolted to a clutch spline, some compliant connector would be good to prevent excess wear on the bearings.