the srt motor will fit, but DAS is right, it will require a bit of tweaking. in the end it will be worth it though. while it is true, it will be cheaper to turbo a stratus motor, there is a lot more potential in an srt motor. 450hp on stock internals, the stratus wont be capable of that. if you want power, thats what you need to look into.
if you are going to do that, make sure you get the entire engine/tranny/wiring harness/computer from the SRT. that will make the install a lot easier