The previous posts are right on the money, but an additional
specification must be included, and that is direction of rotation.

The Ampico pump pulley is attached by means of a screw threaded shaft.
The direction of rotation is indicated on the pump faceplate.  This
large arrow is part of the casting.  Rotating the pump in the opposite
direction will cause the pulley to unscrew from the shaft.

When looking at the faceplate, Ampico pumps rotate clockwise.   So
the motor when viewed by looking at the drive pulley, must also rotate
clockwise.

So the specs are:  1150 rpm, clockwise, 1.5" drive pulley.

(Duo Art motors and pumps rotate counter-clockwise, so don't swap the
motors.)

Bob Taylor