When you look at rims, sometimes they give offset and sometimes back spacing. Offset is the distance from center and backspacing is the distance from the back of the rim.
Rims from an 80's GM truck would be a place to start. They have the 4.56 center like you need. They have 5" offset on a 16" rim, whereas yours is 4 9/16" on a 5 inch rim. So, they're going to be inboard more than the oem, which may create some clearance issues up front.
On the back, You may have some clearance issues with your brake drum size. One fix would be to use drums/backing plates from a 3/4 ton truck. The other fix would be to use Drums/backing plates from a 14 bolt axle.
http://ricksontruckwheels.com/wheels-oe.php
