It surely is a 1 1/8 headtube - the Yo I had in 1992 still was 1 inch, then they changed to 1 1/8 - and yours was made later. There never was a 1 1/4 Yo Eddy.
I´m about doing the same project, and I just ordered decals from Velocals - you have a great variety of possible colour choices, they...