How to check a M/C for a residual Check Valve

here’s The scenario
I gave upgraded my drums to a full 1973 brake disc/ drum on the 66 Polara last winter

I have a decent pedal but it is lower than I like
I can pump the pedal and the pedal comes to a higher height as compared to a single pushing of the brakes
I adjusted the tears thinking that the rear drums needed to be adjusted to get s good pedal height
Not the case here
So I’ve read about the residual check valve helps this situation
My question is that since I am running a...

How to check a M/C for a residual Check Valve
Author: Mr. Fix it