How much more is it worth?

As long as you keep records on the replacement restamp and keep them with the car it is legal. What is not legal is selling the car without informing the buyer of the replacement restamped engine. Another words don't advertise it as numbers matching. I never restamped any engines because I really don't car if any numbers match.

Only two numbers need to be there The vin on the dash and the vin on the title. The rest can be gone

When the Duster was wrecked the insurance didn't look at anything but the condition of the car and the Vin on the Dash. The rad support was changed the door was changed and the rear deck was cut out for the roll cage. Data plate in the gove box. Some of you act like these cars were built last year .

They are 50 years old and most have been through many transformations. Original paint Gone, Original Interior gone, Bumper replated, Drivelines changed, Most are memories of the past that we had. Who cares what they were . Its what they are and what you want. I like to keep them as original as possible but I always add my options and changes I like. Once you take on a rebuild its your build not the manufactures . I just saw this Documented 71 340 Duster By Steve Magnante

No drip rail chrome
wrong grille
no rally dash
wrong dash rivets
But just listen to him describe this original 340 car at a dealer

And he is not in prison last I heard LMFAO at you guys