Rear wheel panic stop lockup

[ga-stepside]

Twice now I have had to hit the brakes hard once in the rain and once on dry a road. This truck is C10 with a chevy parts front disc conversion that I did not do. I pulled the rear drums off and discovered what I think is wrong. The front shoe is the long shoe and from what I gather that one should be on the back, not the front. Is that true? And could that be causing the rear to lock up during a hard stop?