1968 327 grease pencil meaning?

[1cuda]

I'm restoring an April 1968 327 for an Australian Holden.
Engine was built at Tonawanda and this is the first disassembly of the low mileage engine.
Please look at the crayon markings and help me work out what they could be.
It's obviously not H5 like the suffix. Has anyone come across anything similar to this?
Thanks in advance.
Frank in Australia

[1cuda]

Engine number

[1cuda]

Side of block