I did the coin return = credit thing on my Paragon in 1982. Removed the coin mechs and installed one of the coin switches so that the trip wire was moved by the big metal tab that usually presses on the coin mech reject lever.
Drilling a hole in the game never occurred to me. I cringe when I see it. Just got an Elektra with a big ol' green video game button installed next to the coin door. Someone made a damn 1" or so diameter hole to put it in there.