2 bolt starters interchange with 3 bolt starters and vice versus. I have ran the same 78 2 bolt starter on a 65 200 and a 78 200.
"In 1977, Ford made two small physical changes in the starter, which did not affect the interchangeability of the earlier units. First, they moved the battery connection from a copper post on the side of the starter case to a two-part female eyelet terminal on the rear plate of the starter. This was done to make room in the case for more windings, which results in a slightly higher torque value on late model units. The other small change was to reduce the size of the mounting surface to save weight. Although you can easily substitute the late model starter into earlier applications, the two-bolt nose will only have two small mounting ears for the bolts rather than a large oval flange. This does not affect interchangeability; in fact, the late model starter will be an improvement on the older design because of its increased torque. To change from the earlier side-stud starter to the later end connection, you need a 10mm coarse thread bolt, which will go through the existing battery cable eyelet and thread into the female eyelet on the end of the starter."