That is the first thing I did too: check the local laws. You want to be certain that such a motorbike is legal, or how it can be built to make it legal. Here in Indiana, I am an employee of the Marion County Superior Courts so, of course, you will frequently hear me say "Check the laws".
Glad to see there are people interested in these motorbikes as far away as Singapore. I am very glad to meet you here. I hope you find the help and advise you seek.