Went back and forth myself with this same thing. Ended up grabbing a used 2019 GT350 with 3k miles for $64k. Yeah, paid a premium, but glad I did over a Mach 1 which was coming in close to the same in my area.
Yeah I think we broke through a new ceiling with this purchase. Prices keep rising for these, but part of me thinks this was more due to the bidding war between two buyers. I had $53k, thinking this was an outlier but who knows anymore.
The info he received at the time was bogus and read like shoptalk from the manager. He did not know the true price of the car, as others have validated. How you feel about his degree of accuracy is immaterial.