Brian, when buying any old and used car, one inspects everywhere, the Golden rule of Old Car Buying. Obviously you didn't inspect underneath when you bought that car.
the ignition amplifier and pickupcoil, also known as Ignition Module, are General Motors Delco parts, available at NAPA and other auto parts. The XJ-6 is full of GM parts, the A/C compressor, the capillary Expansion Valve at the firewall, the Air Pump, the air pump's check valve, the Ignition Module, the Power Steering Pump, and more, so I think if you buy from the Jag dealer, you'll pay a lot, when you could have gotten the same parts from any auto parts like AutoZone, O'Reilly's, CarQuest, Advance, you name it. It all comes down to learning about the car from other owners who have been there done that.
The Series 3 XJ-6 (1979½ to 1987) is the most refined and "finished" of all the XJ series, that's the one to have.
all the bugs were taken care of.
If the car in question in this thread is a driver (engine runs, transmission works, brakes work, lights work, etc.), then even if it has some rust, (which it does not appear to have based on the seller's description), then I think $1 grand is a steal, even if the a/c does not work, even if it needs some interior reassembly.
I assume all of you clicked on the link above (1985 XJ6) in the first post, and that you saw the ad and the pictures. If not, here it is again.
https://salem.craigslist.org/car/344693561.html
if it was me, knowing what I know, and the car was close to me, I would have run and bought it already. It really looks decent. The repairs that it appears to need are (for me) a piece of chocolate cake.
regards,
Ex