OK, I don't know if there's a simple answer to this - If you had a really built engine, that developed lots of power at a high RPM, then the 60 tooth would let the engine breathe better, and you'd probably get a higher top speed.
OTOH, with a mild stage 1 motor, the 60 tooth would just give you more low end response, and probably take away a bit from the top speed.
If you have any hills to climb, or want more acceleration, you'd probably like it - If you just want speed on the flat, you probably will just run into the engine governor's top RPM limit sooner, and not like it. In other words, you'll have a lower top speed, but get there quicker.
I like my set up with the 60 tooth, as it has terrific power and acceleration, but I'm not interested in top speed, as I just ride off road.
Of course, you could just remove the governor, and then the 60 tooth would let you blow up the engine more easily
And, yes, you'll need a longer chain.