Since you are in the market for a high-dollar rebuild, I have some suggestions that might save some $$$ and improved fuel mileage.
Unless you saw some very high EGTs
before, Iíd forget the big exhaust.
Since you are mega high mileage, I assume you run the Interstate a lot. If MPG
interests you, I would heartily recommend converting to a ZF6
manual transmission. I have football knees and have over 280k on the OEM clutch, although most guys feel there are some outstanding aftermarket clutches out there. (Iíll investigate when my OEM clutch wears out). Diesels are tough on automatics and the solid lockup a stick gives you will add 2 MPG
easy. The 7.3 engine has plenty of torque.
Unless your old rig slowed down a lot over the mountains in PA, Iíd recommend leaving the 3.73 alone. You are too heavy for 3.55s and the 4.10 is a waste of money.
The big turbo wonít gain you anything.
Talk to Swamp Donkey about injectors. He is a PSN sponsor and Iíve found him quite sensible.
Unless you thought the old rig was a slug (apparently you didnít) mods that enhance reliability and easy maintenance (I recommend waterless coolant if you are going to rebuild the engine and definitely a new radiator and have the intercooler pressure tested and the pinholes welded up) are more worthwhile than HP-enhancing mods.