I was picturing a perpendicular dovetail SLOT, not a rimfire type dovetail rail.

For 3/8” dovetail rails, I have used several of the inexpensive UTG dovetail to picatinny adapters under red dots or even scope rings.

For an iron sight option, a Marlin style rear sight from Tech Sights may work. They assuredly will fit a 3/8” dovetail, but may not be the correct height for this particular front sight blade. Old Marlin 99 rear sights are quite low, and mount on 3/8” dovetails as well, although they’re quite challenging to find, and oft expensive when found.