You might try Velobase, looking at the Stronglights to find your crank. Their database often lists the correct BB length if your crankset is there.
VeloBase.com - View Brand
Does that model Stronglight crank require special threads on a crankpuller?
Last edited by Dfrost; 07-01-20 at 01:23 PM.
Reason: Added crank puller question.