If you are using a regular freewheel hub with a spacer kit and a single cog, you have a lot of liberty with your crank and bb since the cog can be positioned to match the crank's chainline by arranging the cog and spacers where you want to.
You are going to use a 9-speed 105 double crank and the recommended Octalink bb so your choices of spindle length are limited but you should be fine.