This doesn't have to be an expensive project. If you want to fit the 5.4L supercharged engine, then there's a lot of other driveline upgrades you're going to need and it all costs money (just for the parts). However, you could just fit a 5L N/A motor with some SRT6 brakes and leave everything else as it is (I wouldn't even worry about changing the gearbox). A 5L V8 in a Crossfire will give you all the performance you need for everyday driving and will sound great.