@ bigtubby:
Welcome to the Kaisertuba club
I'd definitely say your "Munster" tuba is a Kaiser. You gotta look at the
overall horn, not just bore size. Even though the .760" bore is smaller than most Kaisers, everything else looks very 'Kaiser' to me - the large size, being rotary-valved (a requirement for Kaisers), height, being a contrabass, etc. Besides, you stated that your 3rd & 4th valves have bores well into the .800"s, so it seems your tuba is dual-bore or graduated bore.
As stated before, classic Kaisertubas are the Cerveny 601, Alex 164, M-W 197, Miraphone 190, and many old German/Czech tubas like yours. All are basically 5/4+, 6/4 size contrabass (BBb or CC) rotary-valved tubas. They are maybe not as fat-bodied as the American 5/4 & 6/4 BAT's, but they tend to be taller and with larger bores.
Btw, it's nice to see that old Shuster tuba being resurrected

Several of us were yapping about it back when it was on eBay.