I don't think #s matching motor is all that critical. Mopars show the motor in the VIN, unlike GM and Ford cars of that era.
What's more valuable is that it has a buildsheet.
Get a date coded, correct 1970 HP (get one with a casting date probably close , but before obviously, the build date of the car; door sticker) if it doesn't come with one and you'll be fine.
Hard to say, but if it needs a hood and a trunk lid, I think maybe it's worth close to $30k if all other body work is done. You can probably finish the car for maybe $15k more, so you have a completely restored, six-pack car for $45k and your time.
Not bad, but is it what you want? You want an automatic with that color combo???
Metro makes awesome door panels so you're set there. Hopefully, the cardboard headliner is in good condition, but Dayclona makes fiberglass repops.