On the carb, there should be a small tab on the right hand side;
look closely, it should have a groove and a threaded bore.
That is originally (for differently controlled engines) the choke cable bracket; well half of it

the rest is a bolt and a washer
it will happily take a control cable, that you can attach to the throttle lever (part a on your pics)
Just make sure you add a return spring to the other side of the throttle, the pedal return will not help
Oh and you would need to disconnet the original machanism of course.
here's a hint:
'sid