I just posted a topic about swapping keys in pure Dos with a TSR last week. But since that is no option I have taken te courage to mod the keyboard itself.
Bought a cheap yihua 936 soldering station and took a picture of the circuitboard and trace the paths of the akwardly placed arrow right and up keys.
I'm relieved that the research and preparation had worked out. The only sacrifice is the right shift key, not a big issue.

The trickiest part is when I can't find a way to solder on the backside, so i had to scratch to unveil the copper and solder directly onto it hoping it would not burn away.

It's a nice cheap little ps/2 keyboard for my Unisys CWD 😀.