Can anyone identify these heads?

@Jadaharabi

Pulled a 727 for a member here yesterday ,out of a 1975 van, and....it has the same weird 348915-A J heads with the digit/letter date code on top, small J on one runner.
1975-1979 so far. That's a spread.
They also have REALLY thick valve cover rails that even look corrected by machine,coarse, for flatness.