The short answer is 1-1/12 inches of free play should be about right. The longer and more complete answer is that a positive pedal stop is a good idea. This can be as simple and crude as a block of wood on the floor or as over engineered as you want to get. My personal choice is to weld a connecting nut available at any hardware store for about a buck to the clutch pedal arm. I use 3/8 in. thread size. I then take a 3/8 bolt and screw it into the connecting nut with the head facing the floorboard/firewall and adjust it so that the clutch is fully disengaged, and just a bit more when the head of the bolt hits the floor. I use a jam nut to keep it in this position. Clutch adjustment comes down to this: the throwout bearing should be 1/8-1/4 in. off the clutch fingers when the clutch is in the up position and fully disengaged when you push the pedal down. Since you have removed the overcenter spring [ unnecessary when a positive stop is used ], you may well have to rig up some sort of spring to keep the throwout bearing from dragging on the clutch fingers when the clutch is engaged. A positive stop isn't really needed when using a Borg&Beck or Long style [ can't hurt ] but it is possible to overcenter a diaphragm clutch without one. A diaphragm clutch is basically a big Belleville washer, smaller ones sans fingers are used in plate type Sure Grips. This was actually pretty common on factory GM clutches in the '50's & '60's. Most knowledgeable Chevy guys used Chrysler clutches [ Borg&Beck style ] in those days since the bolt pattern was the same.