Dumb question: would these be pretty suitable for the PurePro keyboard? Seems largely compatible, switch-wise. Possibly would need to retain a few keys (e.g. - space bar), but it would be pretty neat to have most of the keys transparent.
cbbrowneFor a PurePro you might be better off just ordering a 104 set directly from Signature Plastics. It will be cheaper, faster, and a better fit for your keyboard.
http://keyshop.pimpmykeyboard.com/product/clear-blank-full-104-keycap-sets
This drop is pretty specifically tailored to ErgoDox owners.
You might still need a couple of extra 1x row 1 and row 2 keys for your PurePro on top of the 104 set, and I don't know if you would be able to find a suitable replacement for the spacebar.
cbbrowneWhile waiting for my ergodox to arrive I put these on my Leopold fc660m. They look incredible but you would be better with a set as I had to mix and match a few keys onto the wrong row to fill the board in places. The ergodox set is very specifically tailored to the ergodox.