If the pedal is spongy, there is still some air in there...... Draft a friend, have him pump the brake pedal three times, hold, and then you crack open the bleeders. Go all the way around the truck, starting at the passenger rear, then drivers rear, passenger front, drivers front. Each time, build some pressure, then release the valve. Do that several times at each wheel. See if you get any air. (I am guessing you will.)
If the pedal has a lot of travel before anything starts to happen, rears need a bit more adjusting. When you adjusted them up initially, did you step on the brakes a couple times before/during adjustment?
Did you bench bleed the M/C before you installed it?