The 53 cable would be very difficult to attach to the '70s backing plate. I have the same setup as you have, as do others I have seen.
The best that I can offer is to get a new '70s parking brake and MacGyver it to your '53 parking brake crossbar. I could tell you how I did mine, but I am not proud enough of it to recommend it to anyone.
Carl

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission