Hi Daren,
Here in the UK, when we had to change to unleaded fuel, most of us found our Mk's ran better with one size smaller slide cutaway and an increase of 5 to 10 on the main jets. Then play around with the needle height to get clean running between ½ and ¾ throttle. Super unleaded may need a further increase in main jet as it tends to have a higher viscosity than the ordinary unleaded - apparently the difference is only noticeable on engines with carburettors, as fuel injected motors get a specific amount pumped irrespective of how thick the liquid is!
Hope this helps,
Regards,
Eddie.