I am glad you guys called my attention to this thread! You will have the first Cummins powered 355 that I
am aware of at least. If I didn't already have a V8 model I would be tempted to try something like this someday. Something that I have been wanting to do is to take my 2010 Suburban to a local shop called Duraburb. They will take a customer supplied Suburban, buy a similar model year General Motors HD truck with the Duramax and swap drive trains. They do such a good job that it looks so stock that they have confused many GM dealership technicians.
One of the custom tunes available results in 1,000 ft lbs. of torque and 1,000 hp. I would be able to tow pretty much anything I wanted to with that setup.
I am very interested in watching your build.