Madflyer
Jedi Knight

Offline
Looking at your first pic it looks like the the two planes of the motor mount and the frame are not the same. I do not thing a slotted hole will help as the rubber would be still on a uneven load it all should want to sit flat so a wedge may be your best fix. Years ago my TR 4 1962 had a broken mount ( rubber pulled away from plate ) I did not know that until I lifted the motor one day from the oil pan. Will be good to see your fix. Madflyer