A Detroit 4-53 is a cute engine for a half ton, but will not provide enough torque for an HD truck to do work. And whatever torque it does make, you will have to rev it high to get it. Plus you'll most likely have to use ether to get it started below freezing, especially on the turbo models as they are harder to start due to lower compression. And all Detroits leak like a sieve.
It does however make glorious noise and a lot of it, if that's your thing. And you could probably get 25mpg crusing on the highway around 1800 rpms or so.