radiator/water pump question

'70 and newer water pumps have a longer nose, so the pulley has a deeper offset and can't be used on the early pumps as that would throw off your alignments. Also the later PS pump bracket is not designed to clear a driver's side water pump inlet.
It's best to use the entire front (PS pump & brackets, crank and WP pullies, alt. brackets, timing cover & water pump) off of the same year engine. Early crank pullies will need one mount hole elongated to fit later (LA and Magnum) balancers.
When you start trying to mix & match components you open up a whole new can of worms.