Excellent advice already given, but an alternative solution may lay with the modification of standard cycle cables that have the correct barrel to suit the choke lever. The other end will need a soldered nipple to complete the assembly along with a suitable washer @ the lever end.
Whenever I have needed to make a throttle cable to suit a larger carb I have bought cables intended for a tandem with a screw on nipple @ the pulley end.
Whilst on the subject of cables, I wonder whether anybody has resorted to making their own extra thick front brake cable by modification of a standard set intended for something else. To say that the quality of the Indian produced front disc brake cables is questionable is an understatement! It would be good to know if somebody has successfully modified a stouter cable with the correct pear shaped nipple to suit. All the better if it was, say, 3 mm inner.
(My apologies for the semi-hijack....

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