vin location

[1badmach1]

I recently purchased a 69 Mustang Fastback project that I believe is
a Mach 1, either a 390 or 428 car. The dash tag is missing, and the left door has been replaced. Are there any other places that I might find a complete vin or is there a possibility of a build sheet anywhere in the car?

Are there any telltale ways to tell what the car originally had? The car has power disk brakes, 9 inch rear, trans is a C6 for FE block. It also has motor mounts and exhaust manifolds for 390 . The radiator is a 4 core. The car has original rear valance with dual exhaust cut outs.

Also, a guy told me that the way the front shock towers were factory reinforced confirmed that it was a 390 or 428.

The car appears to be all original sheet metal except for left quarter skin and left door.

Any help at all would be appreciated! Thanks!