Morris Minor Owners Club

Folks, I've just picked up a spare cylinder head complete with manifold attached.
I've not noticed this on previous manifolds, but it has information in the casting regarding gap settings and firing order.
Is this normal and I've just seen very worn manifolds before (pic below)?[frame][/frame]

Stamped on every one.

Incorrect markings, 12 thou and 15 thou surely BMC?

Markings must be pre BMC and unleaded fuel. Thanks for the replies and I thought I might have a rare example.
This one must be in better surface condition than the others I'd come across.
The rest of the head isn't, looks like very hard water had been used in the cooling system and mud-like super thick oil. I hope to salvage something of it.