Why looking for motor when you can use an external sourse of vacuum?
made by yourself and having much more vacuum and cost allmost nothing
first find a compressor from a refrigerator a small one for free from a broken unit
usually they lost freon and put them to garbage but motor is ok .
This is your vacuum pump then you need an electric valve to open and close the vacuum flow
by a foot switch or you can use the "comand" from handpiece sw
for vacuum tank use one empty bottle from freon for free and the valve is from those professional refrigerators controlling the flow of freon maybe you can take one for free from
a repair shop put them to a proper box make the conections and you have a unit free of troubles for the rest of your life
Thats the main plan if you are interested i can give the details.
I made it before give all that money for MBT250 and when i was measure the vacuum in order
to compare the homemade unit was far away better for 2 reasons
2=rapid response bacause of the tank (Pace try to rise vacuum thats why motor has 2 speeds) Tank has vacuum ready at max all the time.