My North Tonawanda Model 188 had a gearmotor installed when I got it.
The organ is more or less equivalent to a Wurlitzer 146 and has the
Wurlitzer duplex roll mechanism installed.  I presume the crankshaft
speeds would be the same.

The gearmotor develops 1/2 hp and runs at 90 rpm.  This would appear to
be the ideal crankshaft speed, but the 1/2 hp motor had marginal torque
so I reduced the speed to about 75 rpm with pulleys.  There was still
enough adjustment left in the roll drive mechanism to run the rolls at
the right speed.  If I was buying a new motor I would get a 3/4 hp 90 rpm
gearmotor and use a 1:1 pulley ratio.

Fritz Gellerman