Go find yourself a Mercury Marauder.
Rear wheel drive, 4.6 litre DOHC, quite spacious with good acceleration. If you really want some pony, look for a Marauder VT. They came with either a stroker crank, a centrifugal supercharger, or a combination of both. Can you fathom 430hp at the rear wheels from the factory?
Even if you got the regular 4.6, MyLittleBlackBird could point you toward some great performance options for it. Yes, I know its a FoMoCo product, but if you crave a powerful, RWD sedan it'* a great option.