[Land-speed] 327 - 350 SBC

[Elon]

As Neil said the only exact way is to look at the serial number. But even
then you can't be sure unless you check the bore and stroke because of the
ease of changing cranks during a rebuild. Not sure of the reason for your
question but it is just too general to answer. If you want a particular
block for a "numbers matching" deal then you have to have the correct serial
number. If you want the displacement then any 4 inch bore chevy with 3.25
crank will do it. Chevy made only three cranks. 3, 3.25, and 3.48 stroke (in
both large and small journal). The 262, 307, 327, all had the 3.25 stroke.
In early years there were engine mount holes on the front. Later, when they
used side mounts, they continued with the unused front holes. In  '86 they
went with a one piece seal crank. (smaller round flywheel mounting flange).
So visually you can tell if it is a pre or post '86 block if you can see the
crank rear. When EFI came in, the mechanical fuel pump boss went away on
some. There are only two absolutes! . . . (2) If you want the block you HAVE
to use the serial number (2) if you want the displacement then pull a head
and check bore/stroke.