[56GMC]

Got a few brake issues on my ‘62 Catalina that needs help from this forum:
1) Power brake pedal started to feel different the other day & soon began to “hiss” when applying the brakes. Pedal does not pump up with engine off and can hear air escaping while doing that. Have a hard pedal now as the brakes work fine in “manual” operation however. Guess the Delco Moraine booster has an internal leak and needs a rebuild or replacement. Any ideas on where to find one? Also wondered what is the usual failure mode?
2) Since I need to pull the booster now would be a good time to convert to a dual master cylinder & split the lines. Anyone have a source or part number? Planning to keep the drums at this time. Appreciate your help!