Does this truck have two adjuster slots on each backing plate ?? Those huck adjusters have to go clockwise to push the shoe out against the drum. Clockwise as you look at the outside of each end of the wheel cylinder. It will feel as if they are going in two different directions because you look at one end of the cylinder from the front and the other from the rear.
If you back off the adjusters, that will make the retraction distance longer, not shorter. I would adjust them properly , then bleed..
