I feel the original posters concern, an important factor is the chosen master cylinder, it is critical the depth of the pushrod into the master cyl piston is deep (like over 1”).
If you used a C3 corvette master (68-70+-) for manual brakes it should be very deep, this depth keeps the pushrod safely captive in the master.
If you don’t have this deep piston well for the pushrod? ….you need it…get another master.
