Shallow Vs Deep Pocket Master Cylinders

[rn2fine]

I have a question related to trucks and Suburbans made around 1972 with disc brakes. I have noticed recently in a catalog that master cylinders come in both what is described as a "shallow pocket" and "deep pocket". The description seems to refer to the depth of the pocket, 1/4" or 3/4", that the booster rod fits into. I ask because when I bought my 72 I immediately put a new master cylinder on it. The pedal nearly touches the floor when braking since I installed the new master cylinder. I am wondering if the original master cylinder was a shallow pocket but the replacement I put on was a deep pocket causing the pedal to travel further to achieve braking. Does anyone have knowledge or experience about this issue? Thanks !!!