383 and 340 (except t/a and aars), I don't think matching #s is all that crucial. Heck, even 440 cars too.
Mopars, it's easy to tell what engine the car is in it b/c it's in the VIN, unlike GM and Ford cars, so #s matching isn't all that critical.
Rare options, color, trans, all help make a car more valuable, but they have to be verified.
Four-speed, N96, etc. options need multiple items to verify. Fender tag AND buildsheet! The latter more important than the former. For four-speed cars, #s matching on the trans helps w/that. But even THOSE can get stamped.
383-auto car, you're ok w/a re-popped tag w/the info you got.