You should be able to get the V10 in a F-450 can and chassis configuration. However those changing from a 6.8L V10 to a new 6.2L V8 Ford find the new trucks get better mileage, have a better transmission, and have about the same power. The extra 2 gears can make it "Feel" like it has more power because it is able to stay in the peak horsepower longer and at different speeds.
I think that the E-350 still offers the V10 with a lower HP rating than was ever in the pickups, and has a 5 speed transmission, so not as good overall as the F-350 with a 6.2L and 6 speed.
Fred.
Fred.