Welcome to the Stovebolt. Youre gonna like it here.
As far as replacing the clutchhead fasteners,it depends what youre going to do with your truck. If its just a driver and youre not concerned with the small details,,just regular hex head bolts and slotted or phillips screws are more readily available than the clutchheads. And theyre alot easier to work with.
If youre restoring to orig. then youll want to replace with "dem dam clutchheads",as thats what youll be calling them by the time youre done.
Good luck on your project...