I think I have everything I need to move forward on this project....except time. I've been focused on my CNC project https://hackaday.io/project/25564-grbl-powered-6040-cnc-mill. I need the CNC to make various parts and mods for the PnP, so need to finish it first. Hopefully wrap that up in a week or so.
Regarding the mods to the PnP head assembly to accept the Juki nozzle changer, I have identified a couple of approaches that should work. One is easy, the other is a bit more involved, but arguably better.
The simplest approach is to just remove the bottom section where the existing bearing/nozzle adapter were fitted. Rough cut on the bandsaw, and surface on the CNC.
The other way is to open up the round hole in the bottom section so that the Juki changer can fit through it. Then (assuming there is enough material remaining) add a support bearing which should help minimize nozzle runout.
Nozzle runout is a concern. The Juki changer secures to the stepper motor shaft with a single set screw, so any slop in the fit will move the nozzle off center. Plus, any angle between the motor shaft and Juki changer will cause the nozzle end to be off center. Ideally, it needs to be an interference fit, and the axial alignment needs to be very precise. Adding a support bearing somewhere along the length of the Juki changer would help minimize that.