Get the clutch linkage working, I presume it is hydraulic, correct me if I am wrong. Fix the return springs or whatever is wrong with the linkage on the outside of the clutch housing. Put the truck in high gear and start the engine, or whatever gear it will start in. Hold the clutch pedal down while starting. The truck will at least lurch and clutch should come free. Be ready to shut it off quick if it does not come free or if the brakes don't work.
If you have the room, joggle the throttle to stress the clutch, that is why I suggest starting in high gear, more stress on the clutch. Keep the clutch pedal down so only the rust is holding the clutch engaged.
If it gets moving and the brakes don't work, shut it off to stop it and fix the brakes.
Nice truck, love the short wheelbase!
