What engine do you have?
The 273 small block cast-iron water pump had the inlet (lower) on the driver's side and was 1.5"D. The later ~1971+ aluminum water pump had a passenger side inlet of 1.75"D. If yours is that, ask for a 1973 318 hose.
The slant six had only one water pump, as far as I know. The inlet (lower) is on the passenger's side and 1.5"D. I just put one one on my Valiant. I used Gates 70776 (recall). Same hose works on my 1965 Dart 273 upper and my 1965 Newport 383 upper, but only because I have non-original radiators in those. It works if your upper radiator inlet is on the far passenger side. If fits like a glove on my slant to snake behind the fan belt, though I think my radiator is the wider one for 65+ cars.
While discussing hoses, there seem to be many combinations. I suspect the upper hose location varied depending on whether factory air or not. I search images on rockauto to find one that appears it will work. Sometimes, you must cut a hose and add a splice to turn it, or use 2 hoses. Hot rodders do that often. One popular upper hose is from Ford V-8 trucks since long with many bends, so easy to fab something, and inexpensive. Most upper hoses I have seen are 1.5"D.