Brake Booster Replacement

[Mel]

New booster and master cylinder from Stude Int'l four years ago.  The seating depth in the m/c was less than on the original m/c and the booster was physically a bit different, larger I think, than the one I took off.  Bottom line, the rod on the booster had to be screwed almost all the way in for the proper adjustment.  Now the booster has failed.  So I'm wondering if I got the correct booster and/or m/c from SI or if my original setup was incorrect.

My m/c is good but I'm willing to replace that as well if I can get the right combination.

Recommendations for the booster, m/c and/or both?  Thanks folks.  I'll appreciate any and all input.