Greetings . . .
I'd be interested in the Date code and Serial # stamped on the pad by the dizzy.
Your combination of numbers seems a bit unique to me. The head casting #3835913 was used on '54 and early '55 engines. It uses the old style 'brass tube' temperature sending unit.
As a '54 or early '55 I would expect it be mated to a #3733949 block. Instead you have a '55-to-April'56 block (#3836233) - as your research has found.
The date and serial will tell the story about the block.
Not sure if it will tell us why they are together.
regards,
stock49