It sounds like you've backed the brakes off too much during the adjustment procedure. On a floating brake assembly like the Bendix system that year vehicle should have, tighten the brake until there is a firm drag, but NOT a total lockup, and back off 10 clicks if it has the coarse-tooth adjuster (without self-adjusters). Self-adjusting brakes with the fine-tooth star wheel get backed off 20 clicks, but the self-adjusting pawl must be released first.
If you back off until there is a slight, or no drag, the brakes are probably too loose. Free-floating brake shoes will drag a little as the adjuster is backed off, unless the brakes are applied after loosening the adjuster, to self-center the shoes again.
Jerry