I have one of those reels, too -- it is significantly over capacity for 828 Bantam film, which is about the same length as 12 exposure 126. The 126-20 would certainly fit. A 24 exposure roll of 35 mm might, depending on your comfort level with cutting the leader and tail at loading time instead of waiting to see where the actual exposed frames are.

For 35 mm, however, even when I cut a half roll in the changing bag to pull test shots, I just use the regular 36 exposure roll.