I am working on a67 with brake issues. Its 4 wheel drum and the rt front keeps locking up when I depress the brake. I have ajusted the shoes and bleed the lines. It has a new master cylinder and a new rt front weel clyinder. Anyone have any ideas. thx

 

Change the front to disc brakes

 

Try replacing the brake hoses over time they deterate on the inside and create a restiction making the wheel lockup.