Help! Intake manifold won't fit!

If you remember, some times at the end a model year run whatever was left in the parts bins were used. My June 67 build date 68 Barracuda had ductile iron rockers instead of stamped steel rockers. The adjusters were at the very top & the car didn't run worth a damn, wrong pushrods. LOL Strange things happen back then & it might be that the PO swapped out the heads & intake. At the age of our cars & as many oweners as some of them have had, it's always a good idea to eliminate any of the odd possibilities.