Well done! Great choice on switching to the Perfect freewheel. It is so much better than the Regina. If the Regina's notches continue to bugger, the best bet is to disassemble the freewheel on the hub, leaving only the inner body threaded to the hub. Penetrating oil on the threads, heat on the inner body, and a large pipe wrench should remove the offensive part. A tire on the rim is helpful during such a procedure.

I hope your Pop's back is better soon and he can get out and ride his Paramount. I've found that the more I ride the less I have lower back issues. All that is needed now is a picture of Pop with his Paramount!