Looking for a firm brake pedal

Yup. Have to change the master. As I said, though, you need to determine if this is simply changed piston stroke, or whether it's a spongy pedal due to air, or other trouble.

In my own case, I went from the factory non power 9" drums on my 67 KEEPING the original master until I found out "whut," and now have 4 wheel discs............

73/4 style on the front, and Lincoln Versaille on the rear. The pedal moves about 40% or so of full stroke, is nice and firm, and stops like nobody's business.

This master DOES have rather small "tanks" so I'll have to keep an eye on fluid. Probably once a year..........check it.