Contrary to what I believed above, there is NO bore reducer used in this application.
Bore reducers are a band-aid approach to fix an issue that should have been fixed by having a matching prop bore tape and shaft sized to that prop. There is no need for one so why complicate matters by installing one.
The guy that I dealt with at NE Prop, said that a propeller shaft zinc would take care of any galvanic corrosion.
(I don't think so
That is the whole purpose of the shaft zinc. Millions of boats out there with manganese bronze props and SS shafts and the only times you see real issues is when there is a DC leak issue, a hot marina or the owner painted the prop with copper bottom paint.. If you keep up with the zinc you'll be more than fine. Just be aware that the PSS, as can GFO packings, may accelerate zinc erosion as the carbon/graphite is very, very noble..
Even your bronze shaft was connected to a steel coupling, which was then connected to an engine with, steel, aluminum, brass, copper and other alloys in it.. That's why you use a zinc..
Even if you try and isolate a shaft with a drive saver you are going outside ABYC P-06 suggested practice, if your engine is ship ground, as most are..