I was able to get enough measurements to decide that the larger DC motor I was looking at would not be a good fit, but the HPEVS AC-20 kit should work nicely. The AC-20 with a Curtis 1238-7601 650A controller retails for about $4250, but can be found for considerably less at emf-power.com. It has been ordered and should be here soon. The AC-20 has a peak HP of 50 and peak torque of 75 ft/lbs. It weighs 53 lbs.
I've also ordered a Mean Well SD-1000H-12 DC-DC converter and expect it by the end of January. It is $300 from JameCo, 72-144vdc in, 11-15vdc, 60A out. It has a couple of interesting features; remote on/off, and 12V 0.25A auxiliary output. It has a 3 yr warranty, and lists a MTBF of 32k hours (3.65 yrs). The Aux 12v out is always on, which is ideal for running the EV Works ZEVA Fuel Gauge Driver Plus, which requires a constant 12v, 35mA source.
In the mean time I've ordered and received several of the small parts I'll be needing to build the bike. I already had the Stebel Compact Nautilus 115dB air horn, it pulls ~18 amps at 13.8v so you MUST use a relay (included) to power it. It can be found online for $40-$50.
The ZEVA Fuel Gauge Driver Plus from EVWorks.com.au will let me use my stock fuel gauge as a SOC meter and my RPM gauge can double as an ahmeter. It cost $225 shipped from Australia.
The Prius inverter cooling pump (OEM # G9020-47031) moves a little more than 20 lpm while using about 2 amps at 13.8v. It cost me $89 on ebay.
I also have a Chennic Hall Effect PB-6 type throttle. It cost $60 shipped from China.