Manifold doesn't line up
Looks like you are in good shape at this point. When you tighten down the manifold bolts the intake will get pulled down some so usually the bolt holes in the head start a just little bit up in the manifold holes. Don't expect perfect allighment.
Once this virus **** is solved we should get together. There's Mopar folks here on the island including the Wagons of Steel race team (all Mopar station wagon drag racers). All my old Mopars are 1970 Darts with small blocks - 3 of them, I've got lots of small block stuff around if you need something. Is the 273 going in your 69 b'cuda?