2¼×3¼ sheet film is not the same thing as 6×9 cm images on 120 roll film. Based on the measurements shared, actual 2¼×3¼ sheet film is about 55×80 mm, while the image opening in one holder was about 53×80 mm.

By comparison, 120/220 roll film itself is about 60 mm wide, and a 6×9 roll-film back may mask to roughly 57×82 mm. So 6×9 roll-film format is close in image size, but the film stock is wider and not a direct substitute for sheet-film holders.

One user who trims film for these holders reported that full 57.15 mm width (true 2.25 inches) will not fit, 57 mm is very tight, and around 56.5 mm loads more easily, with 55.5 mm possibly better for some holders.

So if you need film for a 2¼×3¼ Speed Graphic sheet-film holder, look for actual 2¼×3¼ (also called 2x3) sheet film rather than assuming 6×9/120 dimensions will fit.