Other Head gasket question

[Spheeler]

I took the head off to change the gasket and check the dome size on my fx-1. But it doesn't seem to have had a head gasket previously. Does the little rubber ring built into the Greater girdled head take the place of one ?
Also I couldn't find the dome size anywhere, Is there a way to tell without it being written on them? And should I get new ones because of the damage?
Any help with this would be great, Thanks.

 

[Spheeler]

Pics.

 

[QuickMick]

Yes, the O-Rings take place of the head gasket. I would replace the two on your domes now that you have decompressed them. The outer one is your water jacket O-Ring. Depending on condition you might get away with reusing it.
Dome information should be engraved in the spark plug side of the dome. Get some scotch brite and clean up that side to look for the engraving.