After consideration I think the best course of action is to get the rig to the point that it is ready for it's final exhaust work and take it to a custom exhaust shop that has a reputation for working on Rods and other rigs with special applications. Instead of saying "This is what I want". Ask what they think and if they think there will be any issues with it.
The guy who put 2-1/4 inch duals on my 51 Merc cussed the whole time he was doing it but he turned out a world class job on a car with a stock frame and 2 inch lowering blocks. It isn't something that Exhaust by Mail can handle but it shouldn't be all that bad.
