I can't see your thumbnail image very well, but it appears to be a Rand head. You can use a 1976 CR250M copper gasket to match or cover the dowel hole with a stock FL250 gasket.
Stock FL250's did not come with two dowel holes from what I know. Some other jugs in that era did though.
I was about to post that there were two body types. The one you have doesn't appear like the popular R8501 ads. It appears like the other. Like the ones the team used.
Does it still have it's "gold" sticker?