What I did to make sure I got the bolts correct.... As I took them off the old water pump I put them in the corisponding holes on the new water pump. Then clean the heads off and with a sharpie write letters on the bolt head and the case where they go, just incase one or two fall out when you manuver the new unit onto the engine.
I purchased the BOSCH unit from pepboys, but the one I got must have been moved around in its mold when they poured the metal for the case, cause I had to shave down the idler pulley mounting surface to get the belt lined up with the other pulleys.
I also, as an extra measure, put a very thin bead of water pump gasket silicone just on the outside of the rubber gasket close to the edge, just to be sure it didnt leak, It doesnt call for it but over the years I have changed several water pumps on previouse vehicals and learned ... It sucks when you get everything buttoned up and find a small leak then have to tear the whole thing apart again.
I also changed the themostat and added a bottle of WaterWetter to the new antifreeze, I sware by the stuff....
Also make sure you check the reservoir the next two heat and cool cycles and top off as needed.