Hi, & Welcome to Concours Mustang!!!!
The '66 K GT fastback doesn't look too bad from what I'm seeing-just a couple of observations:
-Its a '66-the engine block should be Ford Blue, Not black-that was 1965.
-Its a Metuchen, NJ plant car by the "Buck tag" on the RH inner fender apron-Check to see if it has "PIO" somewhere on it-THAT itself will tell you IF the car is a factory GT or not-also make sure the VIN on it matches the one on the drivers door data plate and LF inner fender apron-the buck tag may also give some details on other options....
-Also, the fact that its an automatic is a bit rare IF its THE original HIPO spec C-4 unit, and original to the car.
-some small stuff I'm seeing are the decals on the valve covers-these ARE NOT used on Hipo Mustangs, some strange-non-original RED wireing on engine tells me that someone didn't use a correct/original engine wireing harness.
-You need to check the BLOCK just above where the ground for the alternator and battery hook up for the car's VIN
-I'm not sure IF Hipo C-4 transmissions have the car's VIN or not-the 4speeds DO have the car's VIN.
-I'm sure Charles, Jeff and the rest of our gang will chime in on this and render opinions, but I thought I'd start since I'm up super early this morning.
I'm a little hesitant right now to recommend you to the Hipo Mustang site as many months ago it was shut down on us w/o notice and now is back online, I have re-registered with reservations over there and it just doesn't seem the same.....I personally believe the site was sold. BTW I own a 1965 K code GT Convertible. Good Luck!! Please keep us posted!-Rick