Funny that it was already salvage in 1987! You sure you don't have it backwards - the computer was '87 vintage but you got it later? That's when my father bought our first (new!) computer & it was a "turbo xt" (8 or 10mhz 8088).
The very first PC/AT was at most 3 years old at that point & still worth a couple grand. Any 286 would be at least mid-range, as a 386 would probably still cost high 4-figures $.
The hardware was great for the time so I can only guess that small office didn’t need it any more. This was a small regional satellite office of a much larger company.
Funny how that works! My first job in 2001 still had a Compaq Deskpro 386 bought in the 80s to control some very expensive equipment (via some proprietary dongle that wouldn't work on then-modern computers).
My boss at the time told me they paid $10k for that computer when it was new & the equipment it controlled would cost $1-2m to replace (I want to say it was a microspectrophotometer but my memory is blurry), so they had to keep that 386 around & in working order. Luckily these were apparently very reliable computers.
Eventually, the hardware will break, so it's a good idea to plan for that. There are ways to interface with old hardware using new hardware, including special modern motherboards that have ISA slots, or USB2ISA converters
The very first PC/AT was at most 3 years old at that point & still worth a couple grand. Any 286 would be at least mid-range, as a 386 would probably still cost high 4-figures $.