Overheated?

[1987SierraClassic]

Driving home tonight the belt tensioner pulley on my 89 Suburban decided it didn't want to be there anymore. I noticed the steering got a little heavy and the volts went to nothing and figured out quickly that this was "Bad". I managed to nurse the ol' girl home without the temp needle touching into the red zone, but it got really close a couple of times. I tried to watch it really close and drove about 4 miles before I got home...

I'm hoping I didn't damage anything. Will a healthy 350 take that abuse for such a short time? I was really easy on it while nursing it home. Also, changing the tensioner looks pretty straightforward. Any tricks to changing the tensioner? I've never done one and I know there is a lot of tension on the spring.

I'll be severely bummin' if I broke it!