dweller,
I've had problems similar to yours. When the pedal falls all the way to the floor there are two possibilites. One, the master cylinder seals are shot or there is a rusted out spot in the cylinder wall itself. Two, the same conditions exist in the slave cylinder. Whenever I replace one, I always replace the other.
Regarding the excentric in the master cylinder, the Haynes manual has a line drawing of where the excentric should be placed.
The next very important and I mean very important thing about replacing the two cylinders is to use "only" a DOT 4 hydraulic fluid. Any other hydraulic fluid will dissolve the seals in both the cylinders within a year. Take my word for it, as I learned the hard way.
If this doesn't solve your problem, Larry may be right about something sloshing around in the clutch innards.
When you get things worked out, let us know what you found.
By the way, if you get a new slave cylinder make certain that it's the right one by giving the parts clerk the transmission serial number.
Then drain and replace the fluid every year and it'll last longer than you or I.
Ben
www.reproduce100s.com