Chuck - This might be of help. Be Cool radiators makes custom radiators for hotrods. All kinds of shapes and sizes for weird applications (like a blown big block in a 40 Ford (narrow opening). Check their site out at http://www.becool.com/
You will notice that you can call and talk to a tech about your application, and that you can also ship them a stock radiator to clone or use as a base for modification. You can specify dimensions, flange types, cross flow or vertical... check it out.
It is tough to say what their experience in diesel applications is, but I wonder if they can look at the stock 8v71N radiator and answer the question, "can you give me 50% more (or whatever) cooling with your modern materials and methods?".
Might be worth a call. The tough variable to talk to them about is how much airflow goes through the blowers... what is the CFM through the blowers on an MCI?
Craig - MC7 Oregon