<<it simply looks like it was never the right size to start with.>>

That is the way they were. Drop it on there and put it together style. No pressing involved. Slop normal. Extra Crappy.

As I think you said only the top edge of the inside of the race is close to contacting the fork tube. (and that is rather sharp) The edge ends up slowly wearing away at the fork tube. Frightening.

Ive used locktite with good results on slightly loosefitting races with a verticle inside edge but these are tapered. I'd go with JB weld .

Wouldn't put heat to that fork.