That is a great motor, just keep on eye on the trans. The inner chain stretches just like the drive chain and it is not known for its quietness, performance, or reliability.
On the bright side, swapping it to the 7g belt drive setup is a pretty simple swap and is MANY times better so you have that option once it starts giving you issues. They make a 100t that will get you ~27-30mph on stock setup and a harder to find 80t version that does around 34mph and both will be smooth as glass and last many miles.
The HS 49cc will last as long as 3-5 chinagirl rebuilds, around 10k with good maintenance.