That set up looks like it would be perfect. This truck is a water truck. I bought some new 16.00R20 thinking they would work but they have the hutchinson style wheels so now back to the drawing board with some tires and wheels to sell. lolYou can use budd super single wheels in 22.5
I run them on the steers on my 920. 445 65 22.5 tires. Just in budd wheels not hub pilots.
12R24.5s on the rear in dual.
You have to grind down the front drums to fit 22.5 wheels though.
Smaller 385 or 425s would actually help that 7 spd 916. They have a hell of a hole between 3rd and 4th and 4th and 5th where the rpms drop.