EBAY has a set of carbs with choke cable for sale.
One way to get a choke cable.
It says the cable is damaged, but maybe could be fixed ?
https://www.ebay.com/itm/1989-Honda-VTR-250-Interceptor-Carb-Carburetors/362277524158?fits=Make%3AHonda%7CSubmodel%3AVTR250&hash=item54596c52be:g:SrYAAOSwTOtatKEw:sc:USPSPriority!71602!US!4
Ride safely,