I would stay with a 3Hp motor if you have a gearbox. I would run off off a VFD and you would have the same Hp at 30Hz as you would at 60 Hz, motor would be constant torque.
Use a inverter rated 1750 RPM motor 3 Hp, this is an inverter vector type which has a wider speed range ($168). The cost is mostly shipping.
Find many great new & used options and get the best deals for New Teco Westinghouse Motor 3HP 1800RPM 230/460V EP0034 Electric Motor at the best online prices at eBay! Free shipping for many products!
www.ebay.com
There are others listed, if you have a question on one please post a link. Be careful, I had another motor posted, when I checked the specs it had no base/foot. Always check the motor specs online as to the cooling, Hp, voltage, RPM, etc. as they often leave out critical information. Do not assume, always ask if you are unsure.
VFD, these are reasonably priced and fairly straight forward to program. I can provide some general parameters if needed. I recommended making any parameter changes through the software.
GS21-23P0 DURApulse GS20 series AC general purpose drive, enclosed, 230 VAC, 3hp with 1-phase input, SVC, V/Hz, FOC or torque mode $253
Total cost of VFD + motor would be $600-700, but a VFD in this application is NOT a 3 phase power source and requires some knowledge to rewire the machine. Phase Perfect does sell 3 phase power sources that are more less plug and play and similar cost to an RPC, but the issue will still be that the controls are for a different voltage and also the wiring is for the specific 2 speed motor that came with the machine. It is possible to use a step-up transformer but you really do not want to be working with 575VAC and you still need to generate 3 phase. VFD with a good 240VAC single speed motor is your best option in my opinion.
I see you are in Canada, sourcing a motor may be more of an issue to get one shipped to you. Automation Direct I believe ships to Canada. Seems like a lot of high voltage machines are in Canada, this comes up frequently.