Smaller diameter tires and wheels, and a ro-ro bed, it just needs some restorative TLC to be a show car hauler.
I forgot that panorama (the best type ever) windshields survived that long. Might even be the same one that my '56 Dodge panel had. Either, those are 12 year-old images or he hasn't set a date on his camera, yet. I'd drop living quarters onto that frame and turn it into a camper. It's likely got a 440, under that hood. He could probably recuperate some of the loss through selling that and then replace it with a 361 or some other smaller big block which isn't interesting to hot rodders. You don't need a 440 for pulling an aluminum-bodied motorhome, anyway.
This has one of four gas engines available in the C-series trucks - 225, 318, 361, or a 413. The 440 was never available in these. The 361 and 413 are exclusively industrial and medium/large truck engines, beginning in 1967 and going through 1979. Before then, both were car and pickup engines at various times. There are quite a few differences. You'll find 440s used in motorhome chassis from the early '70s to 1979. The C-series could be had with a couple of Diesel choices, too. Regarding the cab and windshield, Dodge used them through many models over many years, in light through heavy trucks, through 1976.
I thought, both 361 and 413's were long discontinued from production. Would be interesting to anyone doing purist restoration, though. Can't see what's in there. But, it certainly isn't the slant-6 of which I don't know why anyone would order one of those for pulling a heavy truck. One has to reckon with pulling a load uphill, with one of those, sooner or later.
The truck 413 and 361 have pretty significant differences over the 1966-earlier engines. The HD truck engines have an 8-hole crank flange vs six, a considerably different water pump housing and cylinder heads, among other things. The truck 413 bears little in common to the hotrod 413 built from 1961-1965; as is the relationship between the 361 car engine and the 361 industrial engine. With the right gearing, the 225 was plenty competent in a medium-duty truck installation.