Well, converting a TOTS Kirk 75 was a tad more difficult than I had thought. After asking the great JC for some advice, he set me straight.
The coating that TOTS applies to the mask seems to prevent the new latex paint from sticking to the surface. If this is the case, strip it well with 91% isopropyl alcohol until the surface feels more “latexy” then (if you prefer) apply a layer of primer before airbrushing commences.
After buying a NAG 75k Castle, nothing compares (in my humble opinion) but I don’t like the idea of wearing it out. So I will rehaul the TOTS Kirk into an H1 as a “stunt mask,” and use the NAG for photos and such. I just hope I can attain a sliver of JC’s talent on mask painting and rehauls.