Dr Diff can fix you up with a 15/16" master. Not sure about a 7/8".

It sounds like a nice light weight brake setup. Also, per my understanding, those front calipers have smaller piston area vs stock and need quite a bit of brake line pressure. On a Cobra based setup in an E I needed a dual diaphragm 8" booster + 15/16" master to get full braking.

http://www.doctordiff.com/