Ray, just a straight on side shot of my truck to get an idea where the front tires lined up with the hood on my fender less truck. Its been a few years, but I believe I built my truck with the idea of possibly adding fenders at a later date (the fenders I had were in really bad shape), but you might want to look a other pictures online to see how the wheel and hood center line up. If I hadn't lost my original pictures I had pictures of the 47 truck that was complete, so that picture may still be floating around out there on line.

After looking at the side view of my truck, it appears to me my front suspension mat be a bit too far forward, but it may be the angle of the pic.

Maybe the center of your front wheels are good, and the rear position of the fenders are good, but the length of the wheel opening is too long. The big truck fenders may be longer in length then the 1/2 ton fenders. Take the extra length out of the center of the wheel well, and adjust the curve of the wheel opening to adjust?

After you reposition the grill shell, maybe you should put the front of the fender into position and mark the center of the wheel, then put the rear of the fender in position, and mark the center of the wheel and see how fat it is between the two marks.