The NV4500 will also allow the use of a PTO for your dump.
I have a 1-1/2 ton with the original 216 and SM420 + PTO and 2-spd rear. This truck is an antique truck and I don't intend to haul big loads on the road, however I do load it to capacity (5 yard dump box full of dirt) and it handles the load fine even on the steepest hills (going forward or backward) - just have to use the granny from time to time and put the rearend in low range.
The 235 in your rig should be even better . . . again, unless you are trying to do 45-55 mph up a steep road hill - but then I would be more concerned about brakes and being able to stop than being able to get up to speed.
For big over the road loads, I have a 366 Gasser/Allison combo in a newer 2-1/2ton. Even it has trouble on steep roads with a full load (24,000 lbs / empty truck weighs 11,000 lbs) - I guess that is what they make Kenworths for.
