engine ID? question

I have 2 /6 225 engines and was wondering where the ID for the engine was.
is it the stamped numbers right above the coil on the blocks machined surface or is it the cast numbers on the side of the block under the manifold?
I just yanked the /6 out of my 66 and want to find out the years of the motors that I have and then choose which one to redo for the driver and which one to use the turbo on.

the first one has these numbers on the engine
8w 225 6079 on the machined surface and
530-7 70898 cast on the block manifold side

2nd engine has
J 225 r 8 18 on the machined surface and
28068307 1032 cast on the block manifold side

I have another one out of a later model truck with peanut head but there is so much crud on it that I can't see the numbers. I'll have to clean that one up some to see if it's a hydraulic (or pop the valve cover and look) motor
if that one is it'll be the turbo unit.

thanks
Kurt