Sorry for the delays everyone! Busy week.
I am using a stepper as my spindle so I can synchronize the spindle with the z axis for rigid taping.
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KIDDING!
Definitely using a brushless motor here; despite being a glutton of engineering punishment, even I wouldn’t use a stepper motor on a spindle! 
Agreed mount is unconventional and could result in forces on the carriage outside the design loads. Alternatively, more mass could dampen vibrations. Planning to test in production.
Motor is 3,000 RPM, 1.2Nm torque peak.Part number 57BLF02
Pulley is 2" OD vs ~1.25" OD on the stock Nomad, hence 12krpm on the cutting tool. I just barely get away with this size pulley on my motor mount packaging. Stock machine runs a 2GT pulley/belt so I stuck with integrating with that. Pulley arrived tonight, just need the belt and I’ll be in business! Stretch goal to bench test the new motor and drive with Nomad control this weekend.
Regarding PCB integration, have slept on it a lot and I think I have a clever seeming way to do it, it’s just literally a matter of time now in the day to be able to flush out the design!