I had the same problem, I could only find one as big as 250 and need about 255mm. I ended up selling the frame out of frustration. The guy who bought the frame had someone cut the steartube in the center or close to the bottom and weld in a small diameter pipe as an extention. With stear tubes as long as these it shouldn't pose a problem for getting the stem in, however it is not something I would want on one of my bikes. I still made the right choice in selling it I think.