If you read the threads in entirety I posted, you will find info on masters from other bikes which do work w/the calipers we have, or ones commonly-mounted in-place of the stockers, such-as the FZR1000 six-piston ones, or the early R1 calipers (not radial mount calipers from the later-model R1's. Unfortunately, those choices are only for the 1993-up bikes, the 1985-1992 models (yours) have a different mounting bolt spacing for the calipers I mentioned, which have a 100 mm o.c. spacing. They also require the 298 mm dia. rotors from the 1993-up VMax models.
Sean Morley does offer a single-sided Suzuki sportbike caliper & rotor setup for the early bikes that the users who have it are happy with the setup. He can probably suggest what matching master cylinders would provide you with adjustable levers, and which may be available from the bike 'breakers' as our British friends refer to used parts entrepreneurs.