An odd combination of keycaps - 1 Ctrl, 2 Alt, numpad keys without arrows, Field + and Field - - what would these have been used for?
The 122-key terminal boards were set up for specific purposes. The numpad did not have arrow legends because the arrow keys are right there. I always disable NumLock (disable to "ON" that is) and I like the clean number keys.
Field + and Field - take the place of normal plus and minus on the numpad. Alt seemed more important than Control back then.
These are interesting but not all that useful, since the majority of people nowadays want to work towards a conventional ANSI layout.
But I would LOVE an IBM cap puller, and those cheap extras could be RIT dyed black for your black set.