To get a standard motor running a bit better I'd use the std carb, a K&N filter element, remove the snorkels from the top of the airbox and fit a better pipe.
The carb will need some rejetting but the difference in performance will be quite noticable.
This way the filter is still protected for Vinduro type riding.
You can go further and remove the airbox and fit a pod type filter but you still need an airbox to protect the filter properly.
You can gain a bit more bottom end by removing one spring off the advance/retard mechanism for the points. This brings the ignitiion advance in a bit sooner.
hth
Brent