Brake pedal is really stiff

I can try swapping my Duster's drums with the Valiant's and see if that makes a differece. The shoes themselves look fine.

Look, you are not listening, and throwing parts around doesn't solve anything.

You need to INSPECT the drums you have to see if they are:

turned out too big

worn "bellmouth" or "round top" or other wear patterns

The only way I know of to do that is put them on a (brake) lathe where you can center them up and run a tool across the surface to test for wear

You need to see if the shoes fit TIGHT in the drum, and the only way to do that is to remove the shoes and trial fit them in the drum. See if they appear to "sit flat" in the drum, whether they "rock" to and fro, indicating drums worn are larger than the shoes

I would agree that you might use a second set of drums for comparison, but just swapping them won't prove a thing.