Can I fit a 655" RB Big Wedge into my Dodge Magnum R/T AWD or anything with a 5.7L engine?

You can fit anything into anything with enough time, effort and $$$. Basically the only thing you may reuse will be the body. The wedge will probably need a beefed up 727 Torqueflite and this will probably cut into the cabin. Front suspension and frame will need to be redone for the weight and size of the drivetrain. Forget any A/C or other luxuries. Floorplan will need to be modified for the driveshaft and larger rearend needed, also you would need to tub it for the rear wheels. Cooling, wiring and fuel delivery will need to be custom designed. Just buy a used funny car, it may be easier.