Stronglight, huh? That makes it more complicated. I'm assuming that's an iso taper (like Campy) rather than jis (like Sugino). I have only limited experience with that.

What I've done in the past is to trial fit the crankset using any BB with the correct interface. That makes it easy to measure the chainline and to figure the spindle length that I need.

I donlt know how much help that is but it's the best that I can do.