I've found things work better for me if I leave the two manifolds loosely attached (they'll wobble around a little), then attach both intake and exhaust manifolds to the head, get them tight against the head and once that is done tighten the intake and exhaust manifolds together where they meet. Hope that makes sense.

Good luck!
Jon

~ Jon
1952 1/2 ton with 1959 235 | T5 with 3.07 rear end