FWD Focus to RWD or AWD?

i have a 07 focus ST it is a 2.3 Liter with a 5 speed transmission. i seen where they made a v8 focus RWD its called a Focus RS i think but anyway i was wanting something different and the RS are all hatchbacks and i have a sedan so i thought it would be really cool but i dont want to have to buy a whole new engine so i was just wanting to turn my motor long ways in the engine bay and put a rear axle in it. but i read somewhere that it is easier to make a FWD to AWD that would be cool too but it doesn't matter which one i convert to they both would be different. i thought for a RWD about getting an axle and suspension out of an old mustang but I'm not sure if any of it would fit. For AWD I'm not sure what i would have to do. I have seen where they sell conversion kits for the V8 RWD but i don't want to spend that much money that is why i would prefer to keep my 2.3 four cylinder motor. I am set on doing one of them i just need some help. i need any websites that would help or any help or guidance you have to offer I would greatly appreciate it!