David,

Block casting 3837004 is a 235 only.
One of the best ones out there.

T56X is here...
http://chevy.oldcarmanualproject.com/chevyresto/56070.htm

Your engine specs.....
http://chevy.oldcarmanualproject.com/chevyresto/56152.htm


-Tom

1950 Chevy 3100 w/ 1956 235