Engine Swap for 77 Born Free?

[Bearskidog]

Greetings,
I recently added a 77 Born Free motorhome to my fleet of vehicles and since it is a gasser, I am looking at an engine swap. This RV is based on a Ford E350 chassis, and has a 460 gas engine with 3 speed auto transmission. I am considering swapping in a diesel engine, preferably a Cummins with 5 speed, but I know that would be a fair amount of messing around to make that work, so I am looking at easier swaps. I know that the E350 chassis was available with the Ford (IH) 6.9 as early as 1983 or 84. So, given that the E350 chassis did not have significant changes for about 15 years, what are the possibilities of bolting the 6.9 right into place of the 460? Is that too much to hope for? The 6.9s and 7.3s are cheap and plentiful as compared to the Cummins. Preliminary comparisons of the RV 460 gas to a friends mid 80s pickup with 6.9 were encouraging.
So, if you have done this, know someone who has, or can point me to a resource to determine the complexity of this swap, I would appreciate it. I have already contacted Destroked and FordCummins, both of which were supportive but they deal mostly with swaps into pickups, not vans.

Lastly, I already know that this does not make economic sense, that I can't save enough fuel cost to pay for the cost of the swap, etc. We all know that any of these diesels will get significantly better fuel mileage than the gas engine. And, the simpler IDI diesel engines could be run on WVO or biodiesel. That is the ultimate goal.

Thanks in advance for your suggestions,
Chris