I just finished modifying my Bridgestone Single Speed Commuter. It's now a fixed gear commuter. I am now using the wheel from my 'Horse with the cracked cassette body by mounting a 16t TomiCog in the disc rotor mount.
The only thing I am unsure of at this point is what to do with the open cavity where the cassette body would sit. The logical thing to do is just mount it back on the axle but seeing that I misplaced it in the big mess that was my garage, that's not going to happen now. I might pull a part off the old Bridgestone wheel that could cover this.