Ok, You kinda gave us what we need when you said that by stroking the pedal it comes up and is hard. This tells us several things. 1) the compensating port is working, and thus the pushrod adjustment is correct. 2) the pedal goes hard, so no air in the system and the rubber lines are ok, and 3) the car brakes and stops normally. These 3 together indicate that the problem is not hydraulic but all mechanical. The problem has to be A) out at the brake drums, or B) mismatched parts.
--Mismatched parts could be A) the M/C physically cannot move enough fluid in one stroke to push out all 4 wheel cylinders to engage the shoes, or B) the wheel cylinders are so big, the M/C cannot move the pistons out on all 4 wheels to engage the shoes in one stroke.
--Inside the drums would be one of several possibilities. A) Miss-adjusted adjusters. As can be seen from the preceding paragraph, the system depends on the adjusters to be set correctly, because the wheel cylinders to M/C ratio has a narrow,one-stroke, operating window. B) flexing. This could be the rubber hoses, or the drums, or incorrectly assembled parts.
--Its been my experience that this type of problem is usually in the rear system. You may find it advantageous to isolate the front/ rear system to prove that.
-The long travel,baring design, on a drum/drum machine occurs when the wheel cylinder pistons are moving, moving, moving, pushing the shoes out to the drums and finally engaging, or ballooning old flex hoses.Thats usually all there is to it. With a small M/C it takes a lot of travel to get the fluid out there. Whereas a large bore M/C pushes more fluid for the same pedal travel. The trade-off is the more leg-power required to stop the car. A larger bore M/C may be in your future.
--Keep at it, and you will find the problem. A hard pedal builds a lot of confidence in the operator. A long-travel/soft-pedal, the way you describe it, is not normal.
-Happy hunting