(wanders in 3 years later):
Yes, it works.
Kaypro 4/83, Gotek using the HxC firmware. None of the hardware upgrades like OLED, piezo, rotary switch, etc. Gotek in Drive A. Had a friend 3D print a bracket / adapter to cover the full-drive bay. I did have to solder on headers onto the gotek to install the HxC firmware.
Used the original kaypro no-twist cable, and bought a 34-pin adapter which I added so I didn't need a pin-to-card-edge adapter. Scrounged a power adapter.
Built a USB stick under dos/windows.
Added the 'Indexed' config file.
Used the HxCFloppyEmulator to migrate a CP/M 2.2 disk image for my K4 into DSKA0001.hfe on that memory stick.
Booting the Kaypro with that USB device plugged in, display went HxC, then 000.
Pressed buttons to 001. It booted.
Now I'm off to figure out what support exists for other drive configs, load the mem stick up with a ton of old images, etc. And maybe I'll do some of those hardware upgrades to the Gotek.
Cheers!