Aloha to you also, are you in Hawai'i?
A late start could explain a lack of traffic & suggestions.
As Terry said, don't jump to conclusions. Probably Not a bad head gasket, nor exhaust valves (I don't know where you could have ever gotten that idea.).
The radiator pressure relieve valve in the center of the cap is rated at 14-18 psi according the manual. The outer cap seal probably can't contain much more pressure, I'll suggest maybe 25 psi.
If the heated / pressurized coolant can't be relieved to the reservoir because of a collapsed bottom nipple on the reservoir, then it will relieve pressure somewhere. Usually from the top gasket of the cap, & wet the top radiator tank. Or from a damaged area.
The combustion chamber head gasket has to contain 100's of psi even during idling. So with the overflow hose disconnected from the bottom of the reservoir, cooling system filled & engine started, lets unplug the fan connector from the radiator sensor.
Now use a piece of wire to bridge the contacts, the fan should now run. Does it? Leave that fan disconnected. Leave the engine running. A Gen 2 fan only runs if key is on.
If you could use a window fan to blow cooling air from the RH side of forks across the exhaust header & coolant reservoir that would be good.
We are looking to get the temp gauge up to about 1/2 scale and NOT have any pressure relief from the overflow hose, yet. If your system was to be relieving pressure below 1/4 - 3/8 temp gauge I'd guestion the head gasket.
When temp gauge reaches 3/4-7/8 scale, reconnect the cooling fan. Does the fan come on? Does it start to reduce the temp after about 30-60 seconds. Note at what temp the fan turns off (1/2-5/8?) & at what temp it comes back on (5/8-3/4?).
The engine & cooling system is NOT overheating unless it is consistently 7/8 - fully in Red Zone.
At least this is what I would do.
Gen 2 normal temps without a Thermo-Bob.
1/4-3/8 scale roliing down the road. 1/2-3/4 scale idling at a long stop light.
With a Thermo-Bob, 7/16 - 5/8 scale most of time. Perfect.