Some of the old school 216 pumps have a different profile of curve in the pump arm. There’s a little concave sweep in it. However, the modern replacements seem to have an arm that appears identical to the 235 versions. My hunch is that either will work, but it’s only a hunch.
I seem to remember someone telling me the 235 pumps were designed to put out a bit more volume, for the extra displacement.
There are many variations in inlet/outlet angle and position. If retaining original lines is of importance to you, consider that as a major factor.
