Broken case: gearbox bushing / sleeper build questions

[2tkwik]

I have everything I need to fix this gearbox issue, however, I would some help on which route to take, and I would like to switch up my build. Sorry if the two questions in one thing is against the rules.
https://imgur.com/a/8Y12WSu
https://imgur.com/a/LapPIr7
(Hopefully these pictures work)
I have a spare stock motor, however, I would like to get away with having 2 motors at the end of this.
My options are:

1. Put a new gear, bearings, and cover on old af16, and send it, I have a new motor if it breaks
2. Run stock motor bottom end for now, try to get old motor bushing sleeved at machine shop (or of one of y’all can do it)
3. Swap cases

My build:
polini corsa
arrow pipe
malossi crank
26mm pwk
Polini ruckus variator
Stage 6 clutch
zx trans
Planning on using 9:1 gears


I would like to make my scooter as quiet as I can get it, while being able to go in the mid 50s with plenty torque. I was thinking about swapping pipes and getting some sort of airbox setup.

What is a good quiet exhaust for my build?
Where can I buy one of those pwk dio air boxes, and would I need a smaller carb due to the exhaust?
Would my transmission setup need to be changed?

Will be updating y’all on the repair or build.

[noiseguy]

I've always thought you could have those case interfaces bored and resleeved. But I've never looked into having it done.