you are on the correct website then ....if you post a want ad for a gauge cluster there will be a lot of replies because there is nothing rare about those gauge clusters used 70-76 in multiple models with only minor differences.
Floor pans can be had for relatively cheap on ebay or some vendors here.
Salvage yards across the country had dried up but this website is an excellent source and there is nothing that goes on a 72 dart four door that cant be had here.