I’ve found the same thing true for all my four current Conns from Bari to Soprano, from 1925 - 1941.
Interestingly, the mouthpiece pickiest of them, the baritone and soprano, have the most perfect scale once the mouthpiece is right. The tenor and alto are less perfectly intonationwise, but I play a standard Link and Meyer on them, which may already be a bit smaller than what they were originally designed for. So from this perspective they are probably just more forgiving and work alright with smaller volume pieces.
Then I have seen advanced players who can play a 10M in tune with a small chambered step baffle Berg style piece and sound really good. I can’t. Maybe I will in many years. But on the other hand, I have actively been playing for almost 40 years and functioning for the music I play, so I might never get my airstream and embouchure to this point.
Regarding the OP I’d put it this way:
Not many people will actually still play a Conn Bari from 1917. So if a saxophone life is saved by keeping the horn active by musicians, any means is acceptable. If a matching mouthpiece is found and a way to intonate the thing, that's great. If not, or if the OP wants to play a slightly more modern piece, I wouldn't say no to modifications, as long as they work.