#2 is a keyboard for an IBM "model C" 3178. I have one in data entry layout. The pocket is for the terminal manual. Almost all the keys send upcodes.
There are four models, which can informally be called C0-C3. If you notice, the block of keys on the far right is in some kind of numeric layout. In other models, it's extra PF keys. On mine it is covered over.
Oh about modding it for use: there might be kbdbabel code for it, but it'd probably be a huge pain. We hope to get a replacement F controller working in the near future, so eventually you could do that. Note the odd enter key placement, it may be even harder to use than an XT, and not all keys send upcodes (like on an XT).
If you are making (or own) a 60% model M or F, 1 or 2 of these model C keyboards have the numberkeys front printed with F or PF, so that'd be useful for that at least.
Not sure about #1. it does sort of look like a DIN connector though. As far as I know there are no IBM branded keyboards that use cherry's MX keyswitches.
I don't think it can be that old, as it says y2k compliant on the back.