I got a 68 Belvedere Station with non-power drums on all 4 corners.
Poor braking power at present. Car just bought.

First of all will replace the Fluid and bleed the system. If this doesn't help I will add new Shoes and wheel cylinders on all 4 corners.
I was wondering if I will replace the Master Cylinder if I can improve
the braking force with another Master Cylinder? OEM it is a 1' unit,
aren't there 15/16 or smaller diameter MC's around? Anyone mounted a
15/16 Disc/Drum Master????

May I use smaller diameter wheel cylinders (A-Body for example) on the rear brakes for improving power on the front?