I would also agree to sell the Topre keycaps, then you can probably buy 2 set of nice MX with the money, or a nice set with some rares.
Single unit E profile \| exist on Italian sets at least, and there are some older boards with 1x backspace like the G80-0528, 0879, etc if you are interested in Cherry keys. I forgot the 1x backspace in the GMK mods buy since it is also common on JIS, kinda feel bad might have had some more Japanese interest too.