Not possible with any of hyosung’s parts. Maybe buy a GV125-S EFi donor bike and try to retrofit everything in to the GT Frame (not easy but not impossible)
Stay with carb, EFI = more problems if things go wrong as they have a LOT (A LOT) of sensors!
Or maybe find some custom megasquirt ECU and learn to program it , and go through some trouble finding needed parts to make GT125 EFi (the effort will mean it is still better to stay on carbs)
// Meditation doesn't mean you have to sit still....