The wheels are 16"x6" with 3.5" backspace.
The tires have a ~6' wide tread.
If I did it again, I'd go with 16"x5" wheel to be closer to the original look.
The 6" wide rim, however, gives a little more options on wheel selection. It also allows the sidewall to stay relatively straight instead of bulging out as it would on a narrower rim. This also keeps the entire tread surface on the ground instead of allowing the edges of the tire to curl up into the sidewall as they might do on a narrower rim.
The truck has stock suspension and stock drum brakes.