Inverter question

Have a question regarding sizing VFD inverters. I have an old Hardinge
chucker with 1hp 2 speed motor. I'm having problems with the antique
relays and contactors and would like to replace all that with an
inverter. There's a couple 1.5 and 2hp inverters coming up on eBay.
Given that I frequently do a LOT of repetitive start/stop at max rpm,
should I oversize the inverter and go for a 2hp?
Given that I want to put a 3-5hp motor in it eventually, could I run the
1hp motor off a 5hp inverter?
I don't mind buying a smaller one now and buying another when I go for
the larger motor, I can use the 2hp on my Bridgeport.

Also, given that I have a two speed motor and what I know of inverters,
I'm just going to have to wire it for the high speed windings. I have a
Toshiba 1hp inverter and I recall reading in the manual that one should
never disconnect it from the motor under load, which would seem to
preclude switching windings. Correct?

Thanks for any advise,

Jon