I bought this 1973 Atala Grand Prix (well, I was told it's a 1973). I need to know what the seat post size would be. Sheldon Brown shows it is 26.8 mm but I bought that size and it's too big. I decided to have it sandblasted and powder coated. I have replacement decals on order and I'm mixing newer components with some of the original components. I'm only about half finsihed at this point.