If your bike is in good condition, as in not crashed or dropped, and you like it other than the running issue, I certainly wouldn't get rid of it. You will get almost nothing for it, and have to pay full price for a new one. Since you have checked all the easy stuff, it could be in the ECU, fuel pump or throttle body. I don't know how you test those. The ignition is simple except for the CDI. If your battery has enough current to start the bike, it likely has enough to power the ignition and EFI systems. I have no idea what the current draw is on the fuel pump, but it might be on the high side. If you have a flooded type battery, I would definitely replace that with a MF AGM type. And make absolutely sure all the wiring is good, especially the ground.
If it were mine I would go with the carb kit. It also comes with a new ignition system, since the ignition and EFI are connected together. I know everybody wants EFI, but I don't know why. It seems to me that anyone who would choose an Enfield over the latest high tech Japanese wonder bike would actually prefer a carb. It seems expensive, but only costs a small fraction of what it would cost for a new bike.