273 commando Build

Exactly. I machined my heads to get the chambers down to minimum but I checked the deck with a precision straight edge and deemed it ok. The Surface was smoother than some of the above photos. Production machining back in the day could be quite crude. A worn out braised carbide tool with a burr on the end could really screw with the finish and accuracy. Those machining marks are a long ways from right and 60 years of engine use can mess with the surface flatness too.

They don't even look factory to me. Seams too coarse for what I've seen.