"So will any 1955 GM truck part work?
. . . some more major parts may differ, but electrical tune up bits will be the same for any 55 235, as well as gaskets .... but call it a "55 Chevy truck", not a "GM" or you'll have'em tellin you GMC didn't have a 235"
There are differences between early USA 1955 235 engines and later USA 1955 235 engines (identified by a "55" or a "255" in the engine serial number). The 6v/12v difference most likely won't affect the "tune up bits", but some of the gaskets will be different.
And, Bill's comment about "GM 235" and GMC not having a 235 is for us Americans. As Bill would know (but, I am only assuming), a 235 engine might have been used in a 1955 Canadian GMC small trucks (a 235 was used in 1954 GMC small trucks).