Help: Brake distribution (prop) valve, 4 wheel disks

Getting my wife's "88 SVO convertible" back on road after neglecting it..
she wasnt driving it anyway.. and found the rear disks, {from SVO
transplant} were barely doing anything to stop the car.

I need a new master cyl, evidently as the pedal drops slow.. but in going
over research, realized I had never removed the stock 88 dist block piston
seal and spring.

Took it apart and taking the seal off was easy, but how do you remove the
spring?

Also... noted that (front to) rear brake line is severely rusted toward the
rear, I want to replace the rusted section while I'm at it..I can rent a
double flare tool but - is this metric or sae line?