I too fathomed (cute pun eh?) the idea, as I have access to a marine unit. My research showed me that the high swirl bowls/heads would show an improvement, but could be cranky to get started when its cold. The zexel pump on a lot of them really isn't "rodable", and to time a 7100 for the marine parts would really make pump tuning kinda rough. The marine engines were set up for fairly constant rpm cruising, and street driving is not factored in to the build. The low end power would be sacrificed for mid and upper range, which would be okay for a purpose built engine, but not necessarily for the street. Additionally, these engine had the advantages of using the world's largest radiator.....an entire ocean. I was told cooling "could" be an issue if one were to turn em up past their marine ratings for the street.

These are not my personal opinions, rather from various cummins factory techs. The ones that weren't afraid to vary from the "scripted" tech advice that is. Trust me every cummins tech knows what we do, they just can't talk about it from a company standpoint.....but once in a while you find a renegade to give the real scoop.

I've heard of a few medium duty 8.3 ram transplants. It is doable, but requires a little fabbing. Though the architecture is the same, the 8.3 really is a bigger brother.