I don't see any reason why you should have such a large gap. If the master cylinder is all the way in the 'retracted' position, whether you have .001" or 100 inches of free-play in the linkage makes no difference to the resting position... however, it makes a big difference when you go to activate the pedal. The less free play, the more actual hydraulic travel you get.
And, especially on earlier model trucks, you want as much travel as you can get due to the firewall flexing and 'eating' up some of the travel.
In addition, you want as much disengagement as you can if you expect the transmission synchro's to last - when you end up only mostly disengaging the clutch, it's really ******* those synchros.
Actually... I'm still not convinced that it matters with this truck. In a different application, where the throwout bearing is /not/ always spinning, I could see it matter, but I'm not sure it makes much of any difference when it's spinning already.
Now, I'm just talking about 'resting your foot', and not putting any large force on it.
Pretty sure that most of the throwout bearings getting worn out on IDIs is due to the grease leaking out more than any other cause.