If I rememeber correctly, my TCR's mount was screwed on, not rivited. It sounds like the OP unscrewed it and removed it, and simply needs to put it back on and buy a braze-on FD for it.
That would be correct, and is part of the reason I've gotten so confused over this whole thing. I knew there were clamp on and braze on FDs. I knew the original one wasn't literally brazed on, so I figured it was some type of older clamp on that worked with a bracket, and as long as I got the correct diameter I could use a clamp on. I didn't anticipate the screw holes getting in the way. Off to ebay. Thanks guys!