LF kelsey Hayes caliper started dragging.

Greetings,
During my resto I converted to a set of Kelsey Hayes. For the first few hundred miles everything worked great. Then the left front brake started to drag and now the car pulls to the left.
Ive read some treads and I am familiar with the knock on these brakes but I replaced the caliper and flexible hose but the left front is still dragging.

What in the proportioning valve could impact just the left ront brake?

1969 340 Dodge Dart
Manual Disk/Drum brake brakes MC36406
Stainless steel hardlines

Thanks

AlV