This website about the diary of Samuel Pepys gives some ideas of matches that were being talked about at the time :
http://www.pepysdiary.com/indepth/2006/08/30/queen-catherines-il/
Apparently many at the time thought that he would marry Frances Stewart out of love, but I think this piece is very interesting:
"The more politically seasoned French Ambassador, de Lionne “told Louis that the meanest of the courtiers was busy in selecting a new wife for Charles, and that
the daughter of the Prince de Ligne, to whom Charles had been reported to be attached during his exile, was confidently spoken of. This would be an alliance greatly backed by Spain, who had had enough of England as Portugal’s ally”. (Davidson, p. 203). Where Charles was so cash strapped choosing between love, money and political alliances only added to the dimensions the courtiers had to consider."
Does anyone have information about this princess? I couldn't find any.