On the 235 there are 3 alignment rings that go into the intake manifold that position the intake gasket. I experienced some vac. leaks as the PO hadn't bothered to install them. It was difficult to get the intake gasket properly aligned, which would also effect the exhaust gasket. Hence, leaks!
If your manifolds were trued as a unit, they should bolt up properly as a unit.
One of the 261 guys should verify that the alignment rings are or aren't used in that engine. Hopefully, this will steer you in the right direction.
