rear disc swap master cyl. residual pressure valve?????, change it or no.. going to junkyard tomorrow... Options

[94yoter]

hey everybody,
I'm going to pull-a-part tomorrow looking for rear disc parts for my brake swap.
i was wondering if the people who did this changed the master cylinder or any valves or not.
i know on some older type cars (Chevys and Fords with 4 wheel drums) they had a residual pressure valve somewhere in the hydraulic system.
this basically kept some pressure in the brake lines so the shoes didn't have to travel as far to contact the drums.
that way they could apply the brakes quicker.
if you converted to discs all the way around they would drag because this residual pressure isn't necessary.

does anyone know if celicas had this or if any parts other than the actual brake assemblies and stuff were needed?

thanks in advance.