When considering engine transplants, everyone thinks of pushing the fire-wall back, whereas, instead, I look at ways to move the radiator forward, even if it requires either the hood/fenders be lengthened, or the grille be re-designed.
I think it's a joke the way the later-model light-trucks of all makes have those wide sloping windshields and ten-acre dash-tops, with the most of the engine tucked back under the cowl.
Just yesterday, I was examining an early-80s F-??? single-axle dump-truck with the original 3208.
The doors, cab, and even the cowl, and possibly.the firewall, were identical to those on an F-150,-250,-350, and I am fairly sure that the wide "hip-fendered" dog-house could easily be swapped onto the smaller trucks.
The next time another one is in the shop, I am going to raise the hood and measure from the cowl to the radiator, and compare the firewall to mine.
Simply swapping on one of those dog-houses and maybe moving forward the front fender mounts might open up a bunch of engine swap possibilities, the DT466 for instance.
Back in the seventies, the F-350/3208-CAT swap was fairly common; I think at that time, the 3208 was more commonly called an 1160.