Check the fit in each side, and if one is tighter than the other, make that the first side installed. I seem to remember the manifold being the tight side, with the rings a slip fit in the head. The important thing is to be sure the ring stays across the joint, and doesn't get pushed too far one way or the other. Even with a good-fitting manifold assembly and a good gasket, there will be a vacuum leak if the rings aren't there.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!