Buy some new bolts to go with that pump! Replaced one on my old 89 and it turned out to be a real pain in the a$$ since it had never been replaced in 15 years some bolts were seized tight. Buy some PB Blaster and hose all those bolts down with the stuff and keep spraying it a few hours before you do the job, as you don't want to snap any of those long bolts off! It is definately a real do it yourself task it's just thinking back about doing that job on my particular truck pisses me off. It's always the "easy" jobs that can turn out to be a real bitch.
Remember that the fan and clutch mechanism has a reverse thread onto the waterpump shaft so undoes clockwise....(facing the car). On my car it had been welded to the waterpump shaft making removal even more complicated! Good luck