All 5.0L's are differnet depending on mods, trans, gear, tune etc.
My personal 5.0L 91 Mustang 5spd car...mods in sig. I shift on the street at 5,900RPM. My car has a sweet spot there. It really moves out well. Others may say, that is too high, but you can feel the power is still there.
I have read 5,600-5,700 is the highest a stock form 5.0L should be shifted, but you are gonna get many answers on this one.