There are almost infinite cobinations of wheels and tires available for your truck. You can likely find a 16 inch tire with the same diameter as the 15 inch tire. There will be very little difference.
A bigger concearn would be if the new 16 inch wheels have the correct backspacing. Modern 16 inch wheels are typically set inward, while the old truck rims from the 50s were generally centered. When the backspacing approaches 4 inches, the tires start to rub on the fron steering components.
15 inch tires are getting increasingly difficult to find, so 16 inch tires might be more available.
I currently have 31X10.5 tires on 15 inch 4wd rally rims from the mid 70s- mod 80s on my 59 1/2 ton longbed. I do not have the factory engine, transmission, or rear axle in my truck, so a comparrison will be apples and oranges. I do like the stance with the 31 inch tires. If I went any taller with the tires, I would likely have to find lower gears. I currently have 3.7:1 rear gears and a 27% OD. This combination gives around 2000rpm at 65mph.
