You'll be fine.

I have a customer who had an 87 corvette with a bunch of motor work. He had a 16 volt alternator built, and it would hold a pretty constant 15.2 or so, at idle. At cruise, it would go 15.8-15.9. He drove it daily like this for over 2 years, without even burning out a bulb. He also claimed that it took time off his 1/4 mile.

Toby