Tom,
That "captain's bar" you see must just be a shadow; there are no bars on either side of the block. The fittings for oil filter lines are the small, 1/8" NPT size. I have two late 261s with the factory 1/2" NPT holes and I put 3/8" NPT threads in the 1954 261 that I have in my
street roadster , and the difference in size is obvious. I will put one of the later 261s in a pickup truck project that I hope to start this summer.
As I said before, the captain's bars,casting numbers, and serial numbers are just evidence, not proof, of what the engine really is. However, I have never heard of a block with 1/2" NPT fittings for the ol filter that was not a 261. All full-flow conversions that I have seen used the 3/8" NPT fittings, but that is not proof that there is not a 235 out there with 1/2" fittings.
Hoyt
