I think the only real distinction to the fingers is that the side E on older Conns is flat (you know, like the Mark 6!) and of course it's a trivial job to put a cork ramp if you want it; and the distance between LH1 and bis Bb is greater. The LH table is subtly different.
There is absolutely NOTHING wrong with "ergonomics" of old Conns. I was playing my baritone yesterday and happened to stand in front of a big mirror. I looked at my hands - little fingers comfortably near the rest of the fingers, fingers gently curled and able to rest on the pearls, a small shift of the hands to hit side or palm keys. There is NOTHING wrong with the keyboards of these horns. (I have smallish hands for a full grown man.)