Here's more info and a video on that 16" wheel, it does look about right.
https://www.etrailer.com/tv-Demo-Dexstar-Tires-and-Wheels-AM20766.aspxAnother option is 19.5" though those wheels are harder to find, or more expensive. Tires are pretty heavy duty, good load rating choices.
Some new options, none look right for an old truck.
http://www.ricksontruckwheels.com/wheels-gm-25003500srw.phpHere are some old ones I found and will use on my 1 ton, they can be found on some bread trucks and other 1 ton stuff in the 60's and some later.
https://goo.gl/photos/1mdcjv4QLqPJdKLa7These wheels take an 8R19.5 tire which is about 32-33" tall, a good look for these trucks I think.