Technical strange offenhauser flatheads; thought?

I dropped these heads off with machinist yesterday to see if taking a couple thousands off will clean up pitting...... anyway I google offenhauser heads and didn't find a single set with this style of water outlets (they point straight up). also a couple different front bolt holes than new ones.

any ideas about these? they are sitting on what I believe is a 255 mercury

 

I would say boat heads. I have seen others over the years but not offys that's my two cents

 

I've seen them many times, I think they are just an early style

 

Yes, normal early type. I've never found any real chronology, but I think before 1960's at very least.