Just based on the few photos available this looks like someone built it to keep verses some of the pigs that have popped up lately that look they were fixed up to flip.
Having built a 55 with a 4BT I don’t believe you could build this pig for the asking price even if you did all paint and fab work yourself.
From the ad “Syd Dorn is an auto broker assisting the private owner in this sale” so getting accurate info on the build could be convoluted unless Syd is willing to put you in contact with the owner if he’s still alive. I say this because if you see my 55 pop up on Craigslist for $37,000 you know I’m dead and my wife is trying to broker my stuff for what I told her it cost to build.