When I did this on my wifes 72 I went to AZ and got an aftermarket direct replacement booster. The pushrod in it was adjustable so I picked up the MP adapter to use the exsisting new style master that was on it allready.

I did have to grind the corners of the adapter to fit the rounded contour of the booster and a lot of trial and eror with rear end marking compound to get the pushrod adjusted just right.

Works great

Hope this helps