Happy to provide any guidance on the LinuxCNC side.
If you are able to pull up the manual, then there should be a section on Air Flow and Heat) Dissipation which will tell you how much room you need to mount the VFD. My GS21-22P0 VFD is actively cooled and requires 16 CFM. For this reason, I have it mounted on the wall. Generally, drives require about 50 mm of spacing on all sides.
the drive i am not worried about being in the box, but putting the braking resistor in the box with the drive was more my concern. it looked like they generate some heat from what i was reading about them. this is my first try with a VFD so i don’t know what to expect? the drive itself has the built in cooling fan and is probably close to the one you have. Mine is a GS23-23P0
the drives seem to be well documented but not much information on the braking resistor side was to be found other than size. the one i got is 300 W 70 Ohm size resistor i picked up off of Amazon for around $20 it would not be a big deal just to have it outside the box to be on the safe side for starters until i see how warm they can get. i don’t plan on having a lot of stuff in this box. just the VFD , DC power supplies and some relays to control the spindle.
when i get to the LInux part i am sure i will have my fair share of questions 