If you're saying it's cheaper to put an LSx in a Chevy than to put a Hemi into a Mopar, I agree (not $5000 worth in my experience, though). If you're saying LSx in a Mopar vs Hemi in mopar- I'm surprised. Which is it? Or was this a different chassis entirely?
EDIT:
did you go with shelf headers? Make your own mounts? Found a post from other thread that answered the above questions.