Drmike,
Just installed a similar front disc brake system on my 58 3100 with the main difference being that I'm not using a booster. I'm running the original rear and drums. Very happy with the result as its a huge improvement over the front drums and old master cylinder.
Pedal operation is about the same as you described except it's hard 4" from the floor.
Sounds like you may still have some air trapped somewhere.
Are you sure you have the residual valves installed in the proper direction?
Do you have a proportioning valve installed?
