I have a 6503 crankset that doesn't have a small chainring. It uses an octalink bottom bracket. I want to use it how it is now, with just the two larger chainrings, but I was wondering what size bottom bracket I should use.

The triple says it needs a 118.5 v1 spline, and the double is 109.5,

My question is whether the crank arms themselves are different, or if they're the same and the triple needs a longer BB because of the third chainring.

This triple crank has mounting holes for the third chainring that protrude a little, and could be cut off. I am hoping that with this done it will be compatible with the double sized BB and have the correct chainline.

Thoughts?