I sense there is an atapter in the OPC BB shell to use a 3 piece crank with a normal threaded 1.3 ish inch BB.
Have you considered using threadlock on the bolts that hold your adapter rings together , if that in fact is what you have?

If it is a shell ovalization, going back to a common one piece crank
and banging in the strong stamped cups would probably do a job of forcing it back into shape somewhat.

Ashtabula cranks are pretty forgiving, of abuse and low maintainence , though heavy.