I can tell you they did not........he played with a stock Fort - he did add the lead tape to the sides of the hoop (trend he kept when he swapped to the 200G).
Now the Maxply McEnroe was a virtual copy of the Wilson.....it had the traditional Dunlop long flake and super stiff shaft and they added a beefy and much stiffer hoop.
The Maxply Fort was a very very special frame - it didn't change for close to 50yrs - the flexi hoop and stiff shaft was just majic and that's why just about EVERY player from the late 30s until 70s used it at one time.
You can look up pics from 1981 and clearly see JMac used the Fort -