Do you want a really convenient choke lever adjuster? This is pure luxury and it's not all that hard to make.
You'll need a shifter. I happen to like stem shifters on a motorized bike. I can change rear chain rings with either hand. Plus the left side stem shifter is not needed. So it can be put to this use. But a thumb shifter or twist shifter would work, too.
stem mount shifters.JPG
Run a cable from your shifter back to the choke.
choke from front.JPG
You'll need an "L" bracket. On my bike this was just a bit awkward. With the offset intake I had to make a bracket that sticks out just a bit. On a bike with the carb set right along the axis of the bike it'll be a lot simpler.
choke from side.JPG
This probably doesn't need much more explanation. You can see how it's all done, I'm sure.
The L bracket forms a stop for the cable. Slip a return spring into the center and a cable clamp to hold it all together.
Now you've got a good choke adjustment on your handlebars.