The gasketed surfaces match up, but not the bolt angles.
People have "made" them fit, elongating the bolt holes to the different angle, and using wedge-shaped washers under the bolt heads to accomodate the different seat angle for the bolt heads. You also need to consider using sleeves on the bolts to accurately align to the ports, since the '65 and earlier (in addition to the different bolt angle) used 5/16 intake bolts as opposed to the '66 and later 3/8" intake bolts. Not using some kind of sleeve on the bolts allows excessive fore & aft movement of the manifold, allowing for port misalignment.