The Dextar wheels you're looking at should work fine. Another option would be wheels from an E250/350 Ford van, which are very common. I have heard reports that some have had to use a 1/4" spacer for clearance at the tie rods. Just from the description, the used set of wheels you have are for an '88 or newer truck, which will not work on the older trucks without an adapter/spacer.
