Pre 66 intake bolt modifications info neeed.

getting the hole to work is the easy part - the bolts are at a different angle. In addition to enlarging the holes you need washers cut to correct the seating angle of the bolt on the manifold. It's not too difficult if you have a good machine shop - take a rod the outside size of the washer you want, have them bore a hole through it the size for a 3/8 bolt and then have them cut thick washers off the rod that provide the correction angle. This is what a friend did to install a rare Edelbrock D-64 dual plane, inline dual quad manifold on a 318. God is it fun when the other 6 bbls kick in!