Those master cylinders are fairly easy to 'rebuild' with new seals. So long as the bore isn't pitted or scored and the piston is similarly clean, a seal kit (I believe it will be the SP1963 kit or equivalent) will take care of the master cylinder. It's probably worth your while to rebuild the slave as well.
Toughest part of the whole job is getting at the slave to R&R or even just to bleed the system. But it's doable from underneath or, at worst, by "gutting" the interior and removing the gearbox cover. That takes time but does vastly improve access!