Keith,
These numbers from a 1948-1951 Shop Manual are not going to explain anything.
1948 Engine Specifications
Bore:
216 3 1/2"
235 3 9/16"
Stroke:
216 3 3/4"
235 3 15/16"
HP (SAE)
216 29.4
235 30.4
However, the Shop Manual only gives specifications for one size crankshaft, one size connecting rod, and one size piston. There might be different sets of rings (216 vs 235)? In 1950 and later, there was a different style of one compression ring on the 235 compared to the 216.
Maybe someone can answer your question and explain the increased stroke?
Sorry about not answering your question.
Tim
