I don't see a chain holder boss there; but the angle is wrong for that anyway. I see a little "diving helmet" cable stop at the usual location. The combination of the screw-on cable guide under the BB + stamped dropouts + the brazed on cable guides (forcibly removed) makes me guess it's a lower end bike of mid-80's or later. Like the Record Clubman posted above.
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● 1971 Grandis SL ● 1972 Lambert Grand Prix frankenbike ● 1972 Raleigh Super Course fixie ● 1973 Nishiki Semi-Pro ● 1979 Motobecane Grand Jubile ●1980 Apollo "Legnano" ● 1984 Peugeot Vagabond ● 1985 Shogun Prairie Breaker ● 1986 Merckx Super Corsa ● 1987 Schwinn Tempo ● 1988 Schwinn Voyageur ● 1989 Bottechia Team ADR replica ● 1990 Cannondale ST600 ● 1993 Technium RT600 ● 1996 Kona Lava Dome ●