Making progress........
Managed to get the mill home in my wife's mini-van, disassembled it into three pieces. Loading was easy, four "He-man" at the pick up location man handled it into the van , and then I pulled it up and out the side door with a chain lift. Then built a rolling base to get it to its new home location. I'm not sure how much it weighs but must be in the ballpark of 450-500lbs. I have a used 1.5HP, "Inverter Duty" 240V, 3-phase motor with the same frame size as the original on order.
I also picked up a used but supposedly good Altivar 31 VFD which is now wired (less the motor side). The VFD has three-phase input, however it's rated for 3HP, so hopefully the DC bus will not have excessive ripple. This VFD detects loss of phase, however this alarm can be disabled. I will try it with the alarm enabled initially to get a sense for how hard I have to push the machine before the VFD has excessive ripple.
I would like to perform a preliminary function test of the VFD, test: forward, reverse, speed etc. If I were to try powering the original 600V motor (no load) with the 240V, VFD do you think it will spin with the reduced voltage?