Hi, I don't have any experience with that specific gear or the gy6 engine but I do have longer gears in my old 2 stroke.
If you have the power( and considering you have a BBK you do) the longer gears will make everything more enjoyable as your rpm's when cruising will be much lower and it will take some strain off the engine.
You might need to change your rollers and clutch springs until you are happy with the new setup.
Cheers
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