1965 Mustang brake problem

there are two sizes on the lining of the shoes ,you will  note the shoe with short lining goes to the front , the one with the longer lining goes to the back , also check if any oil is leaking from wheel cylinders that is the leading cause of lock up when you adjust make sure that wheel adjuster is working the properly, the adjust is proper when the shoes are making contact with the drum so you should fell alittle drag when you turn the drums ,good luck .

I would first check the hose, it is most often the cause. When brakes on locked up open the bleeder, if they release the hose is bad not letting fluid return to master cyl