What is your environment? Why is it non DMX? Is this a fixed installation? If so, it's even more prime for DMX control since you don't have to move cables around from event to event.
Otherwise, no. You can't Get the heavy duty motor and then attach it to a powered outlet controlled by a Variac to adjust the voltage going to it and hope that starving the transfer for AC will give you an adjustable speed. Without using DMX, you won't have any control over that motor. It requires DMX to operate properly.
Personally, for me, I'm happy with 1 speed. My mirror ball doesn't get used much(and my ADJ 8" one is falling apart thanks to my careless crew, has since been replaced, but will replace that with another ADJ 8" ball) and works just fine. Seems to rotate at the exact speed people want.
So, what's the environment?