Reflector depth is about 22mm, as is the OD dia.
Opening is about 7mm, but I was able to squeeze in a xhp70 all the way in there, if that’s what you wanna know.
The tail cap is smaller than the body, as the body screws on just above the fins… much bigger threads.
Driver compartment is 4 mm deep, meaning the driver and ring are about 4mm to the top of the head (just passed the fins).
internal dia of ring is 15mm.

The H1A driver it comes with is a 20mm dia, so I’m not sure if you can fit a 22mm in there, maybe with some work.

Have you considered doing a different light with an xhp70? C8 with an OP reflector would have lots of spill.
But I believe it would be LESS floody than the KF8.
Or a Convoy M1 with a OP reflector and xhp50.
I just did a Convoy S2 with a 3V xhp50, pretty floody.

The KF8 is a real good middle ground for floody with a decent hot spot (with xhp50), should be real good for what you want.
Sticking a xhp70 would make it very floody.