If your shoes are installed correctly and your wheel cylinders aren't leaking, you need to do a proper, by-the-book adjustment on all four wheels.
Don't guess by spinning the wheels. Take them apart and look at all the parts and adjust them according to the manual.
By the way, the right front brake is probably working correctly. The left front brake is probably the problem child.
You don't need a proportioning valve. That's for front to back, anyway, not side to side.
