I should be getting my PM-940 CNC tomorrow, and I also have some concerns about the 1200oz-in driving the Z. I am wondering if a 2-1 belt reduction will work for the z, essentially giving you 2400oz-in... There are also a bunch of guys running gas shock helpers on the Z, so you may have some options vs buying a N42 motor and making new mounts.
PZ
PZ