"Tighten the manifold-to-head nuts. Start at the center and work outward to snug, then go back and torque the three intake-to-exhaust bolts to 22 foot pounds. Now go back and torque the head fasteners to 10-12 foot pounds of torque, again from the center outward."
Just follow the instructions and take it slowly. The important thing is not to over-torque, since the manifolds need to be able to "slide" on the manifold mounting surfaces when they expand and contract because of temperature changes.
I used the Australian gaskets, also recommended on slantsix.org:
Australian Gaskets I have about 600 miles on my rebuilt motor, and have not had any problems with leaks so far.