As to the float height, it should be at 26mm from the lip of the carb body where the float bowl seats to the bottom of the float when the carb is upside down and the float is held so it just touches, but does not depress the float needle.
Mikuni BS34 carbs have diaphragms.
You can do a rough synch on the carbs just making sure, by sight or with a wire, that they open at the same time. By sight, just look at both and make sure they open from a closed position at exactly the same time. If you use a thin wire, you hold the throttle plate just open enough produce a slight drag on the wire which is inserted under the plate, then, with the throttle at the exact same spot, see if the wire produces the same slight drag.
A more precise method is to make your own manometer...but try to get it running on the methods above, that will come later.
What are the idle mixture screws set at? As someone mentioned earlier, go 3 to 3.5 full turns, not flats, full 360 degree turns out to start. The manual says something like 1.25 turns- don't do that.
There is no way to tell you how far the plates should be open at idle. If you can start it, let it idle and screw the idle air screw (between the carbs, the finger adjustable screw, not the screw on the linkage that connects the throttle plates) screw it in for faster, out for slower- it should idle at 1200 rpm. Here is a pic from my '79:
Sorry, don't have a pic from the other side.