I have my eye on a VFD with 240v input to 400v output such as the 1hp gs2 model from automation direct.I think the 400 volt requirement will be the difficulty, although I have heard of people using step-up 3 phase transformers on the output
of a 230 volt VFD but it tends to be an expensive solution unless you get the transformer cheap or free.
Check the cost of rewinding the motor to a lower voltage vs replacing the motor with a lower voltage one.
Mark
Pretty sure this will do the trick. Only thing I'm not sure of is the 2 speed motor and how it would work.That sounds like a good solution, I wasn't sure if something like that was available
Mark
ps I checked their website and couldn't find a model like that- can you post the model #?
M