Look for #s on backside of upper rad support, facing the radiator.
Also under trunk weatherstrip at left quarter, towards the rear, stamped into the quarter weatherstrip flange.
Hemi car may have its unique K-frame, and gussets at ft & rear leaf spring mounts (sounds like no help there), snubber reinforcement, and plated 3-speed wiper motor (though that was an option for all).
Only '69 440 RR would be an A12 (aka 440+6, or "SixPack") - no hood hinges, hood pin supports.
OEM exhaust is likely long gone but also tells which engine; no H means 383, for example.
OEM fuel line size is also a clue, 5/16" = 383.
If underside of floor pans was originally black, L.A. build - all others grey.
There are a couple guys here that can decode even a partial VIN & tell the exact car you have.