The Inliners' site shows block # 3837004 as a 55-57 235. I'm not sure about the FIII5H; could it be F1115H? Sometimes the "1" looks like an "I". F1115 could mean an engine produced in Flint, November 15. For 1957, the "H" suffix seems to indicate a 31-32-36-3800 235. The head casting number is correct for a 1956-62 235. That casting number was also used for replacement heads for 1953 and later 235s. The casting date code behind the starter may also help. For example, F167 would indicate June 16, 1957.
Hoyt
