here's a nice touch.....
several of the guide bosses were broken away at the port end.
i think i figured out why they had machined the entire guide boss from the topside of the heads.

i normally drill and ream for new guides from the bottom.
these were done from the topside, down.
on many guide and seat machines, there isnt enough clearance with the head sitting in the machine right-side-up to get a core drill into the guide.
the guide boss gets broken when you are aggressively feeding the drill through the head, and break through the other side too quickly.
since the bottom of the guide bosses are chipped/broken.....the drilling operation was done from the top>down, and the top of the guide bosses were removed to allow enough room to facilitate getting the drill into the guide.

another possibility is they were done on a milling machine, and they didnt have a roll-over fixture, and just had the head clamped to the table.

in any case....with a lighter touch during the final 100 thou or so of the drilling operation....you can avoid breaking the guide bosses like this......