That is a clean looking setup. In terms of pressures, I do up to 30psi on occasion but to be honest I usually only run like 5psi.
A couple design related notes:
The pressure doesn’t matter nearly as much as where you direct it. Honestly, I’d recommend using the 3d printed part just to hold and aim the air tube.
This eliminates any/all pressure concerns, results in a faster print, and potentially eliminates some hardware from the BOM.
The ideal nozzle is soft and can articulate. The best and cheapest version I’ve seen was legitimately just some heat shrink tube at the end of the air tube to form a long thin nozzle.
For the articulation, one could imagine a ball joint with the air tube running through the center of the ball. That would get you
- depth adjust (slipping more tube through to get closer to the part, pulling the slack to get further)
- height adjust (rotating the ball along the spindle axis)
- Sway adjust (rotating the ball along the x/y axis)
The soft tip prevents catastrophic failure /scrapped parts on accidental collision while allowing you to get much closer to the cutting edge.
The air tube would obviously prevent full range of motion on the ball joint but I’m pretty sure you’de still have plenty to be useful.
That’s all ~theory but I think it checks out and it should be cheaper and more convenient in daily use. (If I make one up myself, I’ll be sure to share it 
)