Hy Shortsbolt6300, welcome, in a lot of ways switching your trucks body over to a newer chassis is faster,easier and you end up with a safer vehicle. The modern vehicles have a wider track, which if using your stock front fenders will have at least part of the front wheel and tire outside the fender. There are at least two different widths of front fenders for your style of truck, the widest ones should contain the modern wheels and tires. A lot depends on what you expect the truck to be able to do, but converting the truck to modern standards in every way but keeping the old base is a very time consuming process and if you don't have the facilities or the abilities to do most of the conversion yourself it will be a very expensive proposition. I am honestly not trying to turn you off, but rather make you aware!
