Look at your photo of the booster- - - - -that looks a lot like a bolt and a lock nut where the plunger pushes the master cylinder. Dimpling the adapter accomplished the same thing, but in case you need to make any further adjustments, you can fine tune it in either direction without doing any more drilling.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!