OK, I may have found a solution.
Today I finished a mash-up of a RS-395 and a Globe transmission. It actually fits together fairly well, but I did use a lathe to trim down the motor mounting plate.
It runs quite smoothly. I also see no reason that a RS-540 or RS-550, and maybe even a RS-775, couldn't be mated up as well.
I will post up pictures tomorrow.
For now, here are some specs:
With RS-395 132RPM 7.8lb ft max torque.
With RS-540 143RPM 18.5lb ft max torque.
With RS-550 164RPM 32lb ft max torque.
These values are based on the following:
117:1 reduction.
76% Efficiency.
Max Torque Spec. 12.5lb ft. (This is an odd spec because from the same sheet, the factory motor produces 16.6lb ft
)
[EDIT]
BTW, I forgot to mention, with the RS-395, this mash-up saves 130 grams compared to a window motor. You gain 45 RPM and maintain the same torque![/EDIT]