1976 duster

Hey all. I have a 1976 duster that I've owned since 1985. It was my first car !
THis car has had several engines, transmissions, and rear differentials in the 100k miles that I put on it from 1985 to 1995. With only chebbies and phords around, my duster became a legend! I have been trying to get the rust fixed and the body straight for a few years now, with poor sucess. Roof is still wavy- someone might have walked on it ...... Front fenders are pretty bad... need replacements ! Replacement rocker panels didn't fit right....
Had a few body guys give outragous estimates for body work that has me discoraged... Any thoughts ????