The 5.0 was made all the way up to 2001 in the V8 Explorer. They were introduced starting in 1985 with the HO engine. Any of these engines can be made to work for you. You just need to change the oil pan, intake manifold, timing cover, and water pump to standard early 302 stuff.

Consider looking for a complete 5.0/AOD combo and then swapping the engine components to get it to fit.