Made an account to ask for help with my Kaypro 10

[smokey347]

So I was directed here from reddit. From what I hear you guys might be able to help me. I'm looking to make an adapter for my Kaypro 10 keyboard. I'm planning on getting the actual machine up and running this summer. Until then however, I'm looking to try out these SMK J-M0404 (short stem, upright) switches.

I've found this post where a guy got it working again, but on an original Kaypro 10 machine. (http://goughlui.com/2012/12/01/tech-flashback-reviving-the-kaypro-4/)

The Kaypro 10 and 4 use an RJ45 jack, and the pins are listed as such in the owners manual, page 13-1, here:
https://cdn.hackaday.io/files/20151862140384/5620701505058721359.pdf
That's a download link too btw, hope that's not an issue, if it is here's an excerpt:

"The 76 key alphanumeric, detatchable keyboard is connected to the computer by four-wire cable and is powered by +5 VDC through the cable. The CAPS LOCK indicator light allows a quick check on whether the keyboard is receiving power.

The impedance of the connecting cable can be a critical factor in proper operation of the computer. Replacement of the standard cable with a phone cord can create malfunctions in signal transmission to the computer. This is because the wire in phone cords is too small; therefore, the impedance over total length of the cord can be too high for reliable operation.

Wire in the standard keyboard cable is 28-gage copper, and the cable length is six feet. Should you desire a longer keyboard cable, restrict the length to not more than twelve feet, and use wire no smaller than 28 gauge.

Keyboard Cable Pinouts

Pin 4 (Black)   - Serial Data out (to keyboard), TTL level.
Pin 3 (Red)     - Ground
Pin 2 (Green)  - Serial data in (from keyboard), TTL level.
Pin 1 (Yellow)  - +5 VDC"

Because of warnings like that it makes me skeptical to immediately try something like this:
https://smile.amazon.com/UGREEN-Ethernet-Adapter-Nintendo-Chromebook/dp/B00MYT481C/ref=sr_1_3?ie=UTF8&qid=1525119831&sr=8-3&keywords=usb+to+rj45

It was suggeted to me that I may need to get an Arduino for an adapter, would I be able to do the same thing with a Raspberry Pi 2? I already have one not it use so it's okay if it's a little overkill, as long as it would still work properly without a lot of input lag.

And I've recently cleaned the keyboard as much as I can without desoldering anything, so that shouldn't be an issue.