Nice find! Too bad it's untested. I've learned that a lot of sellers use that as a way to dump broken stuff they know they can't fix.
Certainly an issue with vintage pc's but not so much with keyboards, especially Model F's. The rule is thumb is that Model F's always work. XT's are harder to test unless you have a vintage IBM pc or a Soarer's adapter. I bought a Model F on eBay and the seller swore that the keyboard did not work and they tested on multiple computers (modern ones). I get the keyboard and it works just fine
Maybe I'm just judging from what I've seen in model M listings--obvious molested Ms that have been put back together to look decent with a 'untested' remark when they should be listed as unworking for parts only.
That's great to hear about your F. That's one IBM that I haven't typed on in decades. Maybe I need to pick one up for old times sake...