Plug chops are a waste of time and money and money. Twisting plugs in and out of a hot aluminum head is begging for messing up the threads.
I don't give advice on non-Yamaha jets. You are on your own. I would expect a #120 Yamaha jet to be a bit lean at 5000 feet. If the bike has a rideability problem due to carb tune, fix the rideability problem. If there is no rideability problem, no sense fixing what isn't broke.
Tune one thing at a time. Which of your changes affected the surge problem? If you tune one thing at a time, you know. If you mess with all at once, you don't. That is why it is so important to do one thing at a time. Main jet first. Needle second. Pilot last. Yes, it is a pain in the ass. Most people are too lazy to tune by symptoms, but every racer does. Therefore, most people never learn to tune a carb.
If you still have surge, there is room for improvement. Keep tinkering.
At what cruise speed does your engine surge?