At 277 ur not gonna pull the hills well unless you get a bigger rear sprocket... with any of this class motors, IMO.
Biknut just did a great photo spread and write-up on a T80 from boygofast.
They are probably the cheapest place to get a kit, and ALL kit engines should be tore down for inspection. Really, ALL...
The vendors that support this forum will definitely give you better service than bgf.
Fun stuff!
You'll like it.
Best
rc