We're glad you joined up.
I've built nothing but two strokes, so I can't tell you much about the Predator. Still, you're in hilly country and you might need a bit more power than the 79 cc will give.
In genuinely hilly country, in fact, more than one engine gear might be absolutely necessary. In that case, maybe you ought to consider a shift kit such as Sick Bike Parts offers.
I've considered it myself. But I don't deal with enough hills to make it a must.
And the frame you've pointed to has a good reputation and it's clearly pretty nice. But I have heard that some knock-offs are not really all that good. It might be smart to stick with the 'name brand'. And that, I think, is Skyhawk. Am I right on that, folks?
Others'll come along with more detailed knowledge than I.
So have fun and best of luck.