That's the one, Auchen, and thanks Michael Angelo and nlerner - I think I will go with 113 because I'd rather have too much room than too little. Thanks for those links Michael Angelo. I think if the crank were brand new 111 might work, but it is from the 60's and has been on and off many a spindle, so I think it might sit a little farther down than it used to.

Many thanks!