Check the web for people who have done it. You'll need a 70cc BBK, 19-21mm carb, expansion pipe exhaust and highway gearing.
Airsal T6 is popular with Kymco engines but some will tell you Malossi is the way to go, others Polini and others swear by metrakit.
Along with those you'll need to adapt your transmission to the jug/ pipe/gearing with new clutch springs, contra springs and a new
variator with a more aggressive ramp angle.