Pretty much no keycaps are compatible with Topre, with the exception of some sets that Topre manufactured (I believe they don't do this any more) and a few artisan keycaps.
The CM Storm Novatouch uses Topre Switches, but has custom sliders that are compatible with MX keycaps. It isn't compatible with Topre keycaps.
Some people have bought Novatouches and harvested the sliders to use them in a Realforce, HHKB, or Leopold FC660C. This is a fairly expensive proposition, though, and you would need to take apart Two Novatouches to do a full-sized Type Heaven or Realforce.
You can also buy one of the keyboards with knock off Topres, which have MX-compatible sliders. The sliders will work in all non-stabilized Topre keys.
I think that one time there was a Topre keyset on Massdrop, but it didn't sell enough to hit the minimum order quantity.