If the gasket proves not to be the problem then elongate the center hole on the intake a touch. Just a couple of thousandths of an inch can make life difficult. Will all of the bolts start with just the gasket? Use the process of elimination to see if it is the gasket or the manifold causing the interference. Stay patient and don't force anything.

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer