Brian,

Chevytrucks.org has an article by Patrick on swapping a later 235 for a 216. Maybe this is what you are looking for.

There have been a lot of postings about the options for putting a short shaft water pump in this kind of swap. Some vendors sell a short shaft pump for the newer engines; or, an adapter plate allows the older water pump to work on the newer engine. The advantages of the adapter plate are (1) the fan is in the correct location, and (2) it looks a little more original.

short-shaft pump

adapter plate

Tim