How much initial timing is too much? Running hot on the highway.

Hooked up the vacuum gauge and the timing light again after dinner. The highest vacuum reading I could get is 14", and that came with the mixture screws turned in all the way and backed out about 1/2 turn at each corner, and initial timing back up to 21 degrees. It's idling at 900 rpm like this, and actually sounds good, revs good, no bogs at all. Temp climbed to 200 degrees sitting in the driveway.