Sounds like a seventies UO-8. Probably around 1973 or so. If the lugs are cut in a kind of art deco step design, definitely; the shifter boss is another giveaway. Probably came original with an ADGA leather saddle.

They make nice fixed gears. Get rid of the steel rims if you plan to ride the bike; they do horrible things to your braking, esp. in the wet weather. I just set one up as a fixed gear myself, around the same vintage. A fun beater bike.