How hard is if to swap a 1971 or 1972 dart front end on 1973 dodge dart sport

I agree...the 71 or 72 look better. As for the side markers, you could always weld them closed and delete them. I spent a bunch of money on side markers only to realize they were in horrible condition so I deleted them. Its all personal taste but hey, it was the goverment that required them, not an automotive stylist.