This bike-1977- has a Sekai 4000 Champion butted tube frame. It rides very nicely, but the lug work is a bit crude by comparison the Brit or Italian 531 or Columbus tubed bikes of the day. It cost $150 for the frame, the 531 frames were about $300 then.
The points on the lugs on the top tube never seemed to be centered; maybe you can tell from these pictures.
Despite not being as pretty(frame is fully chromed under the black paint-might strip it one day) it is a good, very durable frame. I have even modifed the fork and seat stays to take bigger tires. I don't advise doing that-it might break one day.
Luck,
Charlie