This was copied from a factory print.
May seem a bit crude but it shows the location you are looking for on a Hemi base, same location on opposite side.
440- 6 pak shaker base has the brackets in the same location.
Feet brackets were sceduled to be discontinued mid 71 on 440-6 pak bases...later on Hemi bases near the end of production run.
Stud thread size is the same on all bases except the head diameter is smaller on studs used later in production.