Well, to answer your question...

So in fact, I would like to know, if it is possible to have the srt6 engine in the coupe standard crossfire ? if so, what would be the price of it ?

Yes, it is possible to have the srt6 engine in the coupe standard crossfire.

Regarding cost - I have no idea - what's an srt6 engine cost? then add labor etc.
I still think the cheaper option would be to change the spoiler on an srt6 to the NA spoilers.

Or do you just want the supercharger, and not the whole engine?