One thing to keep in mind is if you run a VFD or not, as the VFD can take some of the torque away as you decrease the speed. Since it is only recommended to do this on a 3 phase motor to 50%, I've been planning to use a 2HP motor with a VFD on the Heavy 10 I have. It has a brand spankin' new Marathon 1 1/2 HP single phase motor in the cabinet, which the previous owner bought. I'm definitely going 3 phase with a VFD, though and that would allow me to cut the bottom end speed in half with the VFD.
South Bend did ship 1/2HP and 3/4HP motors on the 9A, but didn't the 10L get shipped with 3/4HP and 1HP motors ?