I won’t recommend the unit I have on my HDZ on an SO3 as I’ve had to take it apart and syringe grease into it’s bearings…
On the Pro, from what I’ve read your options are
Stick to 65mm (800W or 1500W) spindles
Wait for the HDZ option for the Pro
The GPenny spindles appear to be of consistent quality, the CW3000 clone chillers are popular for cooling them. I’d order from GPenny direct on AliExpress for price.