ANSWER:

No problem in marrying her if he had repented and it was not well known to the public that he is an openly fornicator. 

Whether he marries a good Muslimah is a separate issue but he must sincerely repent to Allah for the grave sin which he has committed. 

I wanted to ask you whether it is allowed for a Muslim who comitted Zina to marry a pure and rithous Muslima (who has not comitted Zina)? And if not what if he repents and becomes a better Muslim, can he marry her then?