In the picture below, spring 503981 should be attached to the pole on the brake shoe at one end (where the 232074 label is) and where?
In one video i saw, the other end was attached to the pole on the back plate, which is what i have done.
But this does leave the top of the other brake shoe until almost no pressure.
The issue i have is all my brakes are locked on - i had to release the bleed nipple to let some brake fluid out a bit before i could get the drum off (despite lots of violence).

If i were to attach 503981 to the other shoe, that would apply pressure to both shoes which might be they released when i have no foot on the brake pedal and my brakes might not be locked on.

Or (as often is the case) am i missing something?

If your brakes are locking on and you need to release the pressure, then the matter cylinder push rod likely needs adjusting, if it doesn't return far enough then it can't release the fluid

All the brake springs I’ve ever fitted are a complete mare to get on. I would suggest if it isn’t or you havnt lost at least a pint of blood your doing something wrong. They should be under ridiculous knuckle skinning pressure at all times.