John,

There are 2 or 3 easy ways to ID/distinguish a 235/261 engine.
The "Captain bars can be confusing on 1953/54 235 engines compared to 54 and later 261 engines.

If the Engine Serial Number has not been changed, that is the best code:
Find and post the Engine Serial Number that is pressed into a "ledge" in the block to the rear of the distributor (shown at the link below).
Also, find and post the block and head casting codes and date casting codes for both.