Looking for a quality 68-72 A-Body

I did see that one - unfortunately its a engine swap to a 360 from the original 318 which is where I stopped.
Looks like a nice car. It has been on the market for a while at a reasonable price especially for a dealer.
There are just not any nice A Bodies on the market right now - have to wonder where they all are. I found one in Canada but it would take 6 months to title it here in my state so I passed.
the insistence of a "numbers matching" car shrinks your sample size considerably. i personally wouldn't have a problem with a 318 car getting a 360, 340 or a magnum, but i can certainly understand and appreciate your position. after all, it's your money and you want what you want. but i'm not telling you anything you don't already know.

here's another at a dealer/auction that shows nice at first glance. 1970 Plymouth Duster 340 - cars & trucks - by dealer - vehicle...
the claim as to a rotisserie resto a few years ago is a little little suspect. but it is a legit 340 car by the VIN which would suggest the fender tag matches. i read the inspection report on it and came away a little less than thrilled. not exactly turned off, but not wowed. at, or near, that price i think there's better out there.

this one here looks absolutely the nuts and the price reflects that.
https://ventura.craigslist.org/cto/d/santa-paula-1971-plymouth-duster/7589271097.html
there aren't a ton of pics, but from what i can see the work looks to be good. if it were a 4spd car and was highly optioned from the factory i could see it commanding very close to that kind of loot. one thing is for sure, you couldn't build it for that...

again, in the name of transparency, i don't have any affiliation with either of these cars.