‘71 340 Duster Front Drum to Disk with Factory 14” Rallye Wheels - Problems

You confirmed 14x6 so those are definitely aftermarket wheels.

Factory SBP rally wheels were only made in 14x5.5"

doesn't matter what your broadcast sheet says, the wheels on your car are aftermarket.

how or why would a vendor swap his now used and ground on brakes for something else.