You can look for a turntable motor as a repair or upgrade part sold by some turntable manufacturers. For example, VPI sells a stand-alone motor assembly called the SAMA. I don't know if it will have enough torque to spin up your huge platter in a reasonable amount of time. Your patience/willingness-to-wait-for-spinup will determine this. (I remember years ago, some turntables came with low torque motors, and you had to give the platter a shove with your finger to help it get started. Otherwise, you would have a looong wait.) Also, do check with the table makers for belts that are long enough for your set up.
If you can find a motor with enough torque to satisfy you, a number of power line conditioners for turntables offer fine speed adjustability.
I am using a VPI SDS power line conditioner. It allows fine tuning of the frequency of the power wave that is supplied to the turntable motor. This works for hysteresis synchronous motors (including the VPI SAMA), which are most of what is used today. VPI's web site lists their product line: www.vpiindustries.com.
If you come up with an induction motor, you need to get a power line conditioner that allows you to adjust the voltage supplied to the motor rather than the frequency. However, induction motors are considered not as good for turntable applications due to their lesser speed stability. Good luck.
If you can find a motor with enough torque to satisfy you, a number of power line conditioners for turntables offer fine speed adjustability.
I am using a VPI SDS power line conditioner. It allows fine tuning of the frequency of the power wave that is supplied to the turntable motor. This works for hysteresis synchronous motors (including the VPI SAMA), which are most of what is used today. VPI's web site lists their product line: www.vpiindustries.com.
If you come up with an induction motor, you need to get a power line conditioner that allows you to adjust the voltage supplied to the motor rather than the frequency. However, induction motors are considered not as good for turntable applications due to their lesser speed stability. Good luck.