As of Monday morning, the car was still available. I made an offer last weekend and it was accepted -- but logistical complications due to distance and buyer/seller mismatched work travel schedules through October made the deal fall through.
The seller is a straight shooter and a nice guy. The entire history of the car is uncommonly well documented. AFAICT the car is a very nice, mostly original 300 (one quarter panel superbly repainted by a previous owner, carb and radiator replaced at some point, electronic ignition (points kept for next owner), new top -- though it needs the rear window top piece replaced). What the car needs is pretty straightforward.
I want to give a public shoutout to Welder guy
, who was incredibly generous with his time and expertise and went to inspect the car when I couldn't myself. Thanks also to @71Polara383
for also sharing his expertise regarding the few repairs that the car needs.
I really wanted the car as a companion to my Polara, but it was not meant to be -- I hope it finds a good home.