You're in for an aggravating job if you decide to replace the belt and do it
yourself.  I did it a while back on that engine in a '92 Cutlass Supreme.
Be sure to not contaminate the new belt with and oil, etc. and be sure to
replace both the idler pulleys when you do the job.  In my opinion, you
really should get a factory service manual or a subscription to
alldatadiy.com before you start on this.  It's very easy to get the belt
tensioner either too tight or too loose and that thing is a knuckle buster
to reinstall.  There are a couple special tools involved.  The cam holding
tool can be fabricated relatively easily.  The cam pulley removal tool is a
little more difficult.  I went to my local GM dealer and the service manager
was good enough to let me take pictures of the tools and as I had a lathe
and milling machine, I fabricated the cam pulley removal tool myself.   If I
had it to do over again, I'd have paid the dealer to do the job.  You might
try going to the newsgroup alt.autos.gm and asking for help from "Ian", his
screen name is shiden kai.  Hope this helps and good luck.

Garrett Fulton