Pondering with my layout for an upcoming project I was actually wondering, wouldn't upside down R4 keys be handy for those who like inverted bottom row keys?
Some 40s have a split spacebar, with some having a 1U key or two in the middle, and in the case of Orthos, most of the bottom row keys are used with one's thumbs.
So perhaps an upside down cast Lower/Raise button and some other options could proof beneficial.
Just something I was wondering, not sure if it's too late for that now, but think about it. (Although it might become a 40s++ by then, heh.)