wanted 4 bbl manifold

There is a slight difference in the intake to head bolt size and angle but easily adjusted.
So is there an advantage to altering an intakes bolt holes to work with your 65 heads ?
Yes. Any dual plane intake will give you better low end torque.
Any cast iron intake weighs approx. 50 pounds so shipping is costly.
Aluminum intakes ship for cheap by comparison and perform better too.