[Hanuman]

Photo 1 will largely be irrelevant to any but those in the QA process. Especially now. At the time, it would help identify a number of things-

Which casting moulds
Which production batch, etc.
If a major defect, say metallurgy, was identified, they could focus on particular batches, or particular suppliers.
If the final machining process started having problems, these marks might identify which blanks were a problem. Maybe a worn pattern.
You’ll see similar things in plastic components all over the place.

The base casting number is another matter. That base casting will then go on to be used for any number of applications, with minor variations, depending upon the final assembly.
For instance, if memory serves, the base casting on a WR head is actually the same as that on several normally aspirated, 5 cyl coupes. It’s just a mechanical 5 cylinder head configuration.

Some of that detail used to be easily looked up, back when John Griffiths, et al, were part of the system.

If you look with a critical eye at a number of WR heads, from several years, you’ll see some large variations in the castings.