I recently bought two NOS rings for a Stronglight 93 on Ebay, a 48t outside and an inner 40t. Both are hard sizes to find. It came to $65 + shipping. I wish I could remember who the seller was, because I think he had more. I believe he was in Belgium.

Yes, the Stronglight and Campy crank can use the same spindle if you're willing to settle for + or - 3mm. It works for me.

The cups on my Gitane are Campy NR, but I'm not sure which spindle I ended up using.