Are you sure its overheating and you don't have a timing pickup going bad?
Not sure what year they switched from points to a pickup.

Way back in the 80's, a friend had a low rider that fried its timing pickup in the city. The bike ran fine then did not run at all, although they can go intermittant.
He put points on the bike as it was cheaper, and not subject to overheat failure.

Hard to keep an air cooled motor cool in the city, the mixture has got to be on the rich side to get away with it.
Pull the spark plugs and see if they are white (lean).


My last ride was a 1969 Triumph, and I set the carbs up correctly, and could ride 2 up in thick sand at low speeds on very hot days and just managed to get the oil temp up to 180F.

Ring seal and bore size also come into play, when I got my brand new 1979 Triumph Bonneville, it ran HOT, would not idle well in traffic, popped back through the carbs, had detonation even running premium, but after 10,000 miles things wore in and all the problems went away.
The old Triumphs ran aluminum pistons in cast iron cylinders, and the pistons would get hot and expand to a press fit in the cylinders, which would increase heat a huge amount. Heavy scoring on the piston sides.
After 10,000 miles, the parts wore in and the bike ran MUCH cooler.

Brett