In a pickle 70 valiant pitman replacement

The FSM does show a gap between the box and the pitman arm when installed- remember, there needs to be a gap for the jaws of a puller to fit in there for servicing/removal. 1/2" seems about right to me... If my "senior memory" isn't failing me, I believe some replacements come with a thick foam rubber washer/seal that fits between there to keep things clean, but I don't see it in the FSM. Long story short, if it went together smoothly to this point I think you're okay. The nut should be a locking type, and it won't spin on freely by hand. Torque nut to 120 ft./lbs. for power steering, 175 ft./lbs. for manual. Recheck after driving.
Edit: Replacement nuts show up as a nut w/lockwasher instead of a locknut, but same torque specs apply.