ASH302, the kit you've linked to is Metco's solution to a lower crankshaft support pulley alternative to the stock component that Ford came up with. It's definitely a nice kit, but it doesn't have the cage support the stock pulley does, which puts strain on the crankshaft snout. Crankshaft snouts have been known to break off with the use of Metco's kit, but usual cases of this sort concern engines with aftermarket belt tensioners and *big* boost. So you have to be careful with Metco's kit, as it eliminates the cage support.
Here's a few pictures of a rebuilt stock component, which 311-420 is referring to:
Here's a picture of it installed:
Unfortunately this component is long-discontinued from Ford, including the bushings, which definitely take a beating.