The original master cylinder and some replacements already have residual pressure valves built in.
Find out what you have before adding other things.

A check valve is a bad idea, unless you want your brakes engaged always.

The residual pressure valves are a type of check valve but only hold the listed pressure, freely return excess pressure. The brake shoe return springs should be able to provide more pressure than the valve is rated for.

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
---All pictures---
"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-