With the water pump, you may want to see if the original pump is still available. There are a lot of pumps listed that will fit your engine but they are light duty and have a smaller shaft and bearings. This lighter pump will work and fit on the engine, but the heavy duty fan clutch, and fiberglass fan, will soon take a toll on the water pump bearings.
For my 8.1L GM engine I could get water pumps that cost from $75 to $350. I got one of the few remaining Workhorse water pumps and it is much heavier than the other available water pumps. If yours isn't leaking, I'd keep it as long as possible.