for the cable choke you can use it from motorcycle supplier.
i bouht 2 cable choke but at the end i dont use it because you start your engine by hand propping and in that case you stand outside behind the engine near one carb. its easy to pull the choke, start engine an push choke back to normal position. and its enough to use only one choke but if you need both (i dont belive), you can reach it as well.
so you save weight and a lot of work.
i use 2 keihin carburettor copies (Koso) from china. they work well and the hand choke is perfect. If pulled it stay on choke on position (up) and after start you need only to push it back.
it is exactly that one in the link, check the pics, on second you see the choke knob.
https://www.amazon.com/dilei-Carburetor-replacement-applied-scooter/dp/B0718XS5T9/ref=sr_1_1?ie=UTF8&qid=1499353487&sr=8-1&keywords=26mm+keihin+carburetorfor this you can use all parts that work for polini pwk, keihin, koso...and much more.
Edit:
the knob choke like this in the link below works well on mikunis and all the other carbs i wrote.
i use the same.
http://www.nichecycle.com/ncs/mikuni/parts-by-category/choke-assemblies-plungers/vm16-210a-choke-plunger-by-mikuni.htmlThe choke on Mikuni VMs (and as well in Keihin, Koso, Polini) work in following mode: if pulled up, it allows more gas get sucked by the engine in idle mode,so the mixture get rich.it mean if you have the right idle setup on warm engine, on cold engine let the carburettor in idle mode and pull the choke knob, dont touch the gas lever.if the carb is opened too much, the suction is not enough to allow the additional gas get sucked into the engine.
if your cold engine starts well on 2-3 hand proppers without choke, probably the idle is too rich. You can check it on warm engine in idle mode. If you pull the choke the engine should immediatly significantly rpm down or stop. If nothing occurs, is a little lean and should checked, if rpm increase, the engine is very lean in idle and damage can occur.
ceers