I've not long finished fitting the 140cc Lifan into a postie bike. If you're interested I can provide the details on how to do it. Now that I've done one it would probably only take me about an hour to do the complete conversion. I have my bike listed on Ebay so you can check out the pictures...
Possible problems with rego
In NSW, although it isn't published as vehicle standards bulletin, any changes above the maximum original engine capacity for the bike, eg 105cc for a CT110, technically requires an engineer's certificate. Not all AIS staff will know this, and if your bike was...