To me, It is worth more with a black interior. There are lots who say it is worth less....
Ok, sorry to be against the tide but IMO the burnt orange interior would be very different in a sea of black interiors. Black interiors are pretty common. I'm not even sure if you can get all the parts to correctly restore a burnt orange interior. I saw a black '70 Challenger with a burnt orange interior and it was stunning.
IMO, the question was would it decrease the value and I would have to say yes, but by how much, who knows. It's not like the question of the numbers matching drivetrain or something like that caliber, IMO. I would think a different interior, if it's more pleasing to the general public, may not effect the value too much. (Unless you put a green interior in a purple car or something like that...)
Biggest thing is what color you would prefer. Not everyone likes the burnt orange interior, despite it being the original color. Somedays I don't like the original color of my car, Super Blue, and wish it were a black car....