DADS50,
Mine wasn't quite that bad but same problem. Make a cardboard template of the shape of the cowl. Measure how wide the gap is and use the template to mark your cut on the fender that far below where it's touching. Don't cut the flange, make a curved pie-shaped cutout on the exposed part of the fender and then bend the flange to the contour of the cowl and trim the fender to fit. It takes a little shaping the flange so be patient. Once you finish all the cutting and bending weld it all back together.
No doubt that you have to fit the cowls to the doors but it looks like the contour of your cowl matches the contour of your door so that is good. If you made it to match the fender it wouldn't match the door. It's a lot easier to reshape your fender than it is to reshape the whole bottom of your doors and cab. Your fix is relatively simple.
