Interesting 531 decal. I've not seen blue before and it looks early to mid '70s style that seems early for the frame? Very nice looking lug work. Columbus heavier tubing would be SP/SPX but 27.0 seatpost. 27.2 would be TSX, SL, 531c, Tange Prestige, Vitus GTI/TXO.
Last edited by esasjl; 02-11-21 at 04:29 PM.