The GE DC300 drives were sold right here on this forum a few years back. Lathehand is the only one I know who actually did the conversion, and he invested in a GE consulting engineer’s time to get all the parameters right. It is a sweet setup. Several others, myself included, bought the DC drives just in case. I don’t think I will ever use mine for the reason stated: the motor compartment on the Sundstrand machine is not long enough to fit a DC motor with attached 2-speed gearbox. Once I have the 59 running, I will sell the GE DC300.
The Sundstrand machine might fit the right 3ph motor with attached gearbox, but it would require some diligent search to find one short enough. I’ve seen some short pump motors on some of the local farms, so I am keeping my eyes open. I have a 10HP Baldor non-C-face motor and a Reliant 10HP VFD sourced on the cheap from Ebay, just in case. I think the low end performance of that combination would probably be better than the Sundstrand.