I believe your 3837004 block casting code indicates a 55-57 235, The casting code numbers on all of my Canadian truck engines, two-235's Chevys, two 261's Chevys and two GMC 261's all followed the USA engine casting code numbers. Only the location of the information was different from the US engines.
The stamped numbers on the flat area behind the distributor is the serial number. Factory replacement blocks may be blank in this spot or have some unusual numbers stamped in by the installer.

1954 Chevy 1300 engine 235 (1959)
1955 (first series) Chevy 3100 engine 261 (1957)
1927 (other brand) Model T- engine 327 (1968)