Ok, so the bottom bracket is Stronglight and I'm 99% sure from other evidence on the internet and on these forums that the threading of my bottom bracket is French or Swiss. So pardon my ignorance

I'm not really familiar with spindle sizing. Would it be possible for me to get a JIS spindle that would fit in between my Stronglight bottom bracket cups?

This is the wrong forum for this, I just realized, but surely one of you guys using old French bicycles has run into this problem before....