So, back to Jeff's question. Can he safely use any 216 distributor (small distributor cap) in a 1957 235 engine? That HRM article gives strong warnings about using mis-matched cams and distributor drive gears.
I'd say to stick with the distributor that came in the 1957 engine.
Now I am starting to worry about using a 1954 235 distributor in my 1960 261 engine.