I took a look at all the close-ups and I am now leaning toward "RUN AWAY". You are in Texas and would have access to low or no rust FGF's locally. That paint looks really thick and like it's hiding a lot. Add the questionable 400 claim, missing trim tag, strange info from the owner about the PHS docs, and the admission that the car has been raced...
I would pass. I think I understand why the present owner has only had it a couple of months - he was not happy about what he has found.
2012 Mustang Boss 302 #1918, Competition Orange. FGF replacement 2006 Mustang V6 Pony, Vista Blue. Factory ordered. 2019 BMW X3 (Titled to the wife, but I'm always driving it for her. So I'm claiming it) Old projects, gone but not forgotten: 1967 FB 400, original CA car. After 22 years of work, trashed by the guy who was supposed to paint it. I had to sell it. 1980 Turbo Trans Am 1970 Mustang fastback, 351C 4Bbl, auto 1988 Mustang GT, 5 speed 1983 F-150 4x4, built 302 1994 Chevy K2500 HD 4x4, 454 TBI