Thanks for the input guys, and feel free to keep it coming!
I'm going to pick up some 4" tubing for the notch and some plate to box the frame when we get that far- the truck won't be on the road right away, so I have some time.
The biggest thing right now is picking up the bolts/nuts for the rear spring hanger, the U bolts/spring pads/plates from Tractor Supply, getting the tires on the wheels, and measuring, measuring, measuring
Ogre, I may have a shot at a 3rd gen rear, and I will be following your steps on reusing the shock hangers (and the shocks you recommended)!