go ahead and replace the clamps while your in there...they are cheap and new clamps will be less likely to fail. also make sure everything is nice and clean and dry on your gasket surface. i like to use a little rtv black sealant along with the gasket. just put some on your finger and lightly apply a layer to the water pump gasket surface and then place the gasket on the pump and then a very light layer of rtv on top of the gasket..then install the pump. both gasket surfaces have to be clean with no traces of the old gasket. give the rtv time to cure, before putting in coolant. you should be good to go. good luck
