Chad
I don't know about the weight of a cummings diesel, but I do know that about 20 different companies sell the mustang 2 front clip conversions for both old Chevys and Ford trucks. Just about any truck I've read on line has this settup, with some pretty hefty big block gas engines under the hood. I'm staying stock right now, just converted front to disc brakes, with a 460 under the hood. Here is one web site that sells front suspension set ups. I'm not familiar with the international front end enough to know pro or con on the mustang conversion, but the above mentioned brands use them all the time!
Zig's Street Rod - Truck Components