My first thoughts.....if the uneven rim will always annoy you, fix it, and enjoy the pipe.
More thoughts....
Are you a collector?
Will you eventually sell off the pipe for an expected profit? It's a worshiped, Dunhill after all....some guys like them.
Will you care if you destroy the value of the pipe if rim is corrected?
How good are you at "fixing" pipes?
Will the rim-job match the rest of the patinaed briar?
If the answer to any question is "I could care less"....then, sand the rim down- so it's even- and smoke away.

)))
I've re-worked many pipes ....even one custom-made pipe...and never looked back with any regrets. Even Dunhill can screw up a pipe.
Frank