I bought this engine about 5 years ago from a guy who told me it was "rebuilt". It has resided in my home garage until being moved to my recently purchased shop. The casting # 3835911 tells me that it is a 1953-55 235, 150 hp, Blue Flame, 2 WP holes, H cam, PG.
The date code is 5 11 4, which I think translates to May 11th 1954.