You didn't mention the jet size's in your post ?
With the float being able to go up higher, that sound's normal with OKO carby's.
The needle and seat has a pin and spring inside it, once the tab on the float arm touch's the pin, the needle is starting to close then.
By the time the pin is compressed 2mm into the needle the seat is closed, but the float is still able to move up a bit more from there
If you want to check your float level, hold the carby like this pic show's
The bottom of the float should be 19mm off the base of the carby with the float just touching the pin on the needle.
Are you running a decent and oiled foam filter on it ?
Not just the oil what the come with, you'll need to buy some air filter oil and spray or squeeze it through the filter to catch any dirt/dust etc
If you haven't oiled the air filter then that will make the bike run lean, especially at higher rpms.
To check the carby/manifold etc for vacuum leak's,
start the bike and let it run for a minute, then while it's still running spray some wd40/degreaser etc onto the join where the adapter meet's the intake manifold, and manifold to head joint.
If the idle speed, or the idle change's in any way then there is your leak.
When you bolted the OKOs' rubber adapter to the intake manifold, if it was done up too tight it might have warped the mounting face of the adapter, it's only 5mm thick aluminium inside the adapter.
That would let it suck air (vacuum leak) past the rubber o'ring into the air/fuel mix coming from the carby and make it quite lean.
You might be able to square up the mounting face by rubbing it across a flat sanding block with some 180 grit sandpaper on it if it has warped.
Also remove the rubber o'ring and make up a new thick paper gasket (1mm - 1.5mm) to the same size as the manifold face.
That also help's lessen the chance of the manifold warping.