Found my dads original 1971 duster!

Ahhh. Good to know! Maybe I should have left it off the build, to keep it original then. If that’s the case. Looks like if might be, since the code for brake booster isn’t on the fender tag
I wouldn’t try too terribly hard to make it a perfect completely original car, you won’t want to drive it. A few selective upgrades (like power disk brakes) won’t hurt value at all and you will enjoy driving the car much more.