New intake for a 273?

65 273 intake bolts are smaller and at a different angle then 66 and up 273,318,340,360.

Newer intakes can be made to work with some modifications around the bolt holes and perhaps some tapered washers.

Start a wanted ad I bet there is a 65 and older 4bbl manifold out there with your new on it.

Alternately you can put 66 and newer 273 heads on it and use a 66 up manifold