This is a tough question to answer with words and not the actual showing and demonstrating. I am not a body man but did take a classic auto body restoration course and did learn some dent pounding. My advice, buy some hammers and dollies and find an old fender and practice. Metal of the old cars is thicker gauge and can be reworked. Metal has memory so you should be able to get them pretty straight without filler or much filler. If you have "oil canning" that requires heat and some hammering. I'd suggest watching youtube and find what you can and practice until you feel comfortable on your own car. Duster quarters have many body lines, and some subtle areas like by where it meets the door jamb. It's hard too see it, but there is a light concave area there. Good Luck.
