Dizzy leaking oil

To solve this, do I just replace the o ring where the dizzy goes into head and connects or is it more than that?

Yep, easy as pie. Take out your dizzy and replace the o-ring. If the oil is also coming out of your VC, get a new VC gasket set. At any rate, these are both easy jobs. Make sure you get a timing light and check your timing afterwards.