I have come up with an idea for moutning this motor in a bike-usable way without nearly as much effort as I had thought, though it makes it a direct-drive, rather than thru a transmission--but it would at least let me test it's usability under power and load.
This is a sketch from the Loooooooongbike thread, where idea pondering while at lunchtime at work inspired this idea:
All I have to build to make it work is a plate that bolts to the hubmotor's magnet ring cover bolt holes, and to the five outer bolt holes on the powerchair motor's rotor face. I'd also want to lathe the rotor outer circumference just a tad, so that the magnet ring will slip all the way down to the tirebead seating ring on it.
The bad part is that the magnets themselves would be loadbearing in this case, unless I also made another ring for the inside face of the ring that extends just a hair beyond them, to rest on the powerchair motor's rotor.
Then I would need to make a plate that is welded to or bolted to the rear triangle of a bike, that the backside of the powerchair motor can bolt to. It has to be stiff as it must bear the torsional forces of the weight of the bike, as it's effectively a single-sided "swingarm" without being a suspension element (fixed in place).
None of the needed things are very hard to do, and would mean I could bolt this thing onto AFAIK *any* existing 9C or MXUS DD hubmotor magnet ring thats' already built into a wheel of any size. Even some GM hubs should fit it, though the bolt holes might be differently sized or spaced on the magnet ring.
I dunno if I will have time to do the experiment, but I'm a step closer now.