Help understanding body part interchangeability

Hopefully someone who has a better understanding of these cars than I do can give me some advice.

I have a 1971 Plymouth Valiant 4 door sedan with a bashed in right fender that I want to replace. I considered just doing some barnyard body work and making the passenger door be able to open again but once I pulled the fender off the car I decided the rust rot made that pointless. So I am on the search for a new fender.

When I go to a place that manufactures reproduction steel body parts (no fiberglass thanks), oftentimes they don't have a fender for a 1971 Valiant. I know that some parts from other A bodies interchange, for example I know the Plymouth Duster from the same era has the same grill as the Valiant and interchanges. My question is what cars from what years have the same fender as my 71 Valiant? Would a Duster or Scamp fender fit and follow the body lines? Take this one for example.... www.autobodyspecialt.com - RH197071DUSTER1971SCAMPFRONTFENDER

For that matter what years of Valiant fenders would fit my 71? Would any third gen 67-73 fender fit?

Thanks guys