I never heard of such a thing.

I believe you're thinking of swapping a Rossi with a Cox Conquest, not a Tee Dee.  That was done all the time.  A simple slip fit, no machining required.

In those days, getting Cox parts was easy, Rossi, next to impossible.  Just slipping in a Rossi pistone' y cylindre' sounded good until you tried to find one.   I went the other way.  I kept my two Rossi's going with Cox parts, until one blew a crank, which I could never replace.

By my observation, the Rossi was over-rated like a Ferrari, and the Cox was underated like a Corvette.  People were conned into going to great lengths to pay $150 for a Rossi while you could get a Cox (just as good) for $40.

That whole issue was buried by Henry Nelson.