I agree with John - the vanes to pump the fluid can wear but you hardly ever see it - most of the time it's the bearing or the seal. If your belt is squealing and not just loose the bearing may be locking up. Fan should spin fairly easy with the belt off. The damper will also make a squealing noise if it is going bad. It could be slipping and not turning the water pump like it should. Bad dampers are not common either but that's the kind of luck I have.
I installed a NOS heavy duty flex fan from a 1977? Tbird with the 400 engine (shown below). The Tbird fan is driven off the water pump which is driven from the damper on the crankshaft. The added resistance from the big fan ruined my damper (made it separate). The link to the fan you posted looks a lot less aggressive than the one I had so it may work.
I should have installed 2 belts and a different pulley to the waterpump before adding the big fan. The 5 blade style fans were standard on the air conditioned cars however they have a dual pulley on the waterpump - just something to keep in mind - maybe someone here is running a 5 or 6 bade fan on the standard set up and will be able to let you know if they have had any trouble - pretty sure I have seen them just can't say for sure as I have not done it.
Most of the time overheating is due to a clogged radiator.
(This was after I added a dual pulley to the water pump but you can see the fan. There was only about 1/4 inch clearance between the back of the blade and the front of the expansion tank - probably the biggest fan that will physically fit in there -
- had to buy a shorter fan spacer too)