As long as you're moving fast enough to keep plenty of air moving across the engine and oil cooler, and it seems you were cruising at 65 mph out on open roads, 300° plus seems a bit excessive even with 95° ambient temperatures. Ride it hard, load it up with a lot of weight, pull a trailer, etc. and 300° isn't unusual at high ambients. Air cooling efficiency drops as ambient temps increase btw.
As Greg mentioned, if you haven't had the engine properly tuned after gutting the exhaust system that will result in significantly lean operation which will build a lot of heat in the heads and exhaust. High exhaust temps will cause hydraulic fluid to boil; since the hydraulic line for the clutch runs very close to the exhaust pipe you need to keep the fluid fresh and use the highest boiling point DOT 4 fluid you can find. Shielding the hydraulic lines (clutch and rear brake) from the exhaust heat is a very good idea on these bikes.
Jerry