Decided to scrap the fuel tank idea and just buy a fuel cell which ill mount in the bed.
Purchased a TH400 and then put in 4L80 clutches and manual valve body with a 3000 stall
Purchased a pair of 3" hooker aero chamber mufflers.
Bottom end is pretty much done.
I sat the cab, truck bed and some guards on just to see how it sits with the new suspension and im pretty happy with it. hopefully the front drops a fraction more when the rest of the engine and its bolt ons are fitted.