Don't take this the wrong way, but if you are doing something as complex as a Cummins swap into your M715, then engine mounts are going to be the easier part.
What are your plans for driveline parts like the driveshafts, transfer case, axles, electrics, exhaust, radiator, etc?
There isn't a book or list, or step-by-step explanation of how to install that Cummins into an M715. Sure, many have done it, but I'd bet every one was a little different.