try a double clutch converter , i like the stock 1900 stall, or even cheaper is the zl1 or boosted caddy converters 2200 stall, $350.
tune out the convrertor lock up until 4-6th gear if its 6 speed. zero out all the clutch slip parameters in the transmission, reduce torque management by 10% , disable v4 mode, delete trans thermostat, and remove the airbox restricton panel between the fender and box, install lt5 tb and 6.2 manifold.. activate Power enrichment at 60% throttle.
i think the factory manifolds are fine, just make a custom exhaust minus the cats and flapper valve,
also the T1 truck has upgraded front rotors and calipers