Can a Ford 3.8/4.2 rev to 6000?

When I worked in an independent shop back in the early 00's when we heard a car pull into the lot with a loud rod knock you assumed it was a ford 3.8. I would say of all the engines I replaced back then the ford 3.8 outnumbered everything else combined by a 4-1 margin. The head gaskets failed at 2-1 margin over everything else combined. These were stock daily drivers, so no, I wouldn't recommend over revving them. I wouldn't recommend under revving them. I wouldn't recommend driving them any further than you are willing to walk home.

A 4th gen f-body with a v6 would be a much better choice for roughly the same money.

I'm a big fan of 3800/5spd 4th gen F-body. They are faster than most people think and have all the usual 4th gen turning possibilities, but with less weight on the nose. 

I actually like 4.2 F150s more than i like 3.8 Mustangs, but that's because of the New Edge Mustang part.  And the pre-new edge 3.8 cars were more or less a joke. However, I could probably go for a 4.2-swapped pre-new edge sn95.