Centurion used the "Lemans" model name for an entire decade, and the model also had some variants like the Super Lemans. The '79 catalog on Velobase shows it at the end of it's run, your example, if it's a Lemans, would be from earlier, more like the green example shown.
AFAIK they have usually had stamped DOs, not Tange forged as yours has....so it might be that those were brazed in later...which would make sense since this style DO is from a little later era that the frame would indicate.