ALL Cummins engines are capable of amazing power. And that engine won't be 'broke in' until well over 100,000 miles. It will need it's first rebuild in 300,000 miles and is capable of a lifespan of well over 1 million miles. The Dodge will be long gone, but the engine you can put into another project. However.......
...it being a diesel, and your'e seeking it's 'break in point', actually means you want to know when your rings will 'seat' into your cylinders.
The answer is the first time you work it hard. I mean really hard. PowerStroke, Duramax and Cummins owners have a saying: Load it down, hook it to a trailer, find a mountain and drive it like you stole it.
Seriously. The block will become heat soaked and the rings will form themselves to the cylinder and after it all cools, your compression will actually be better, making more power with less fuel and presto, more mpg.