I have an ERA 427, so this may not even apply to the FIA and you may really need an adjustable stop of some sort. But ... I called Doug when I was installing my McLeod CTB and he said the footbox is the stop. My clutch pedal arm strikes the back edge of the cutout in the floor and bottoms out on the back of the footbox at about the same time. Note also that there are two holes in the bellcrank. The outer one provides the correct throw for my 3/4" master cylinder. The threaded clevis on the actuator rod allows you to set the pedal height, it does not change the throw distance.
From McLeod, the important thing is to get enough piston throw to move the CTB the .5" or whatever it is, but not so much that you overextend it and blow it apart. They specify 1" piston throw on a 3/4" master cylinder. Other diameter master cylinders require a different amount of throw. You will want to make sure you have this much movement on the actuator rod after setting your pedal stop .. or you may not get full clutch disengagement. It follows that you should make sure you do not have more than 1" of throw or
You may know the rest of this, but here it is anyway .. as I recall, the gap between the TOB surface and the diaphram fingers is supposed to be
.10-.30" when the tranny is bolted up. I lay a straight edge across the bellhousing and use a micrometer to measure the depth of the fingers in several places. Then I lay a straight edge across the TOB surface and measure the perpendicular distance to the face of the tranny housing. Adjust the screw collar on the CTB until this dimension is
.10-.30" less than the bellhousing measurement. You'll have to settle for whatever it is when the hyd lines are pointing to the left (driver) side and the bleeder line is on TOP.
Sam