Who has done a magnum swap into a 67-69 Dart?

Bobzilla may not have been clear enough..........YOU CAN NOT run an LA intake on a magnum engine, unless you drill/ have drilled the head bolt pattern for an LA intake. You can buy heads such as enginequest (EQ) in either LA or Magnum intake pattern.

LA heads, the intake bolts are perpendicular to the manifold -to- head surface

Magnum heads, the intake bolts are perpendicular to "ground level" in other words straight up and down.