Thanks for the tips guys - actually ended up spending 15 minutes with a Dremel and some sandpaper and made the Fobus Glock 21 holster fit. The width is perfect, but the controls on the Tanfo are much larger than on the Glock so I had to cut some slots for them, as well as shave off a little next to the right side grip to avoid rubbing. Then a little chamfer on the front to avoid the front sight snagging and we are good to go!
The end result is pretty secure, I wouldn't do a cartwheel with it (thankfully I rarely do), but it is plenty good enough for IPSC.
Edit: May as well throw up a picture while I'm in a sharing mood