68 Barracuda power drum brakes,peddle hard.

Is'nt the smaller the cylinder the greater the pressure/less volume, Bigger the cylinder more volume/less pressure?

You should "feel" the assistance of the vacuume when pressing the brake pedal engine on! Could also be that the shoes are in the wrong place, Two sizes on each wheel! primary "shorter" one goes in front and larger one goes in the rear. When facing the wheel look at the shoes should have one short towards the front of car, and one long towards the back of car, there is a difference! Ask me how I know? Anyway I would look at that and then you may have a disc car master cylinder? not sure?

A full bleed would be a benefit, start from the passenger side rear, then drivers side rear, then passenger side front and finnaly the drivers side front! I use a 16 oz water bottle (empty) with a 1/4 inch hole drilled into the lid, then a couple of feet of 1/4 inch clear air hose (like on a fish tank) so you can see bubbles in the line! best way I have found, Don't let the master cylinder go dry, keep an eye on it and fill as required! Quick and easy with two people!

Another thought! remove the vacuume hose from the brake booster and plug the hole in the manifold and see if it changes pedal feel!

John B.