the Detroit 6v53, was a 6 cylinder, 318 C.I. with about +/- 115 HP and i don't know about the torque
so it is easier to just buy a Crate Cummins 6.7 than it would be to upgrade the 6v53 "318" to have the same amount the power as the Cummins....
Ditto, A 6V53 is going to weight a ton more.
That 115, was the bottom end, with the smallest injectors. mys 353 was 101 hp, I remember the torque was a lot more then a 360. I had N40 injectors, (2 or 3 steps above the smallest), I kept trying to get a set of N60, or N70, but back then they were $125-$150 each, and I needed 3. And a turbo, but neither ever worked with my budget.
I got that truck back in 1984,(engine was already in it), and ran it for at least 10 years, before I sold it.
Thing got 27MPG around town, down the highway, pulling a trailer, any where, but took 2-1/2 weeks to get moving from a stop, but once moving nothing slowed her down.
In 86, I took it to Chicago, to help my sister build a deck on her house. My sister kept getting mad, because everywhere we stopped, someone would come up and ask if it was a diesel, and I would talk to them a bit. She had just bought a brand new Mazda RX7, and my ugly old truck got more attention then her brand new sports car.
Only reason I sold it, is the single seat truck, and the load noise does not go well with raising a family. A good bit of that sound, is from the gear driven over head cam, & accessories., and the gear driven blower, no way to easily quiet it down.