While butchering it for the reeds may seem a good idea, I would personally prefer that you really didn't do that. Old rarish instruments are disappearing all the time.

Actually, the wonderful sound you get out of that box may well turn out not so good when you transplant the reeds. There is so much more to the sound than JUST the reeds - the whole tone chamber construction and indeed the whole instrument affects the sound - the type of wood, the size and shape of the passages and chambers, etc. My little 32 Bass Settimo Soprani has a tremendous sound, and it doesn't have special reeds, just fairly 'standard' ones for the day - it's the way it is made - the 48 bass model Settimo Soprani same period is nowhere the same even though it seems to have identical reeds from the same manufacturer, even though the 32 bass model was aimed at a 'cheaper audience'.

"keyboard reconfigured to this four-row style"
As far as I understand that sort of instrument was not totally uncommon to be a standard design (many were probably discarded or butchered once the 'piano' style became trendy) - whether that idea preceded or postdated the addition of the real piano keyboard by Pietro Deiro (allegedly in 1920) I wouldn't know. It may have been 'liberated' or bought. If it was something very special, and thus possibly quite valuable, obviously the relatives didn't care a shit...

I suspect it could easily be about the 1920 vintage.

The B switch I guess might be the master switch - if you listen to what they do, you should be able to work out (or even look if you have it apart) what reed combinations are controlled, and how they are interlocked. I suspect it could be a 3 reeder. If you are already a piano accordion player, you should be able to manage working that out.

Robin