You can also search on:
http://www.cuda-challenger.com/
http://www.moparts.com/
FED 387 is correct. E-body standard V-8 K-members will accept a small or big block with only the correct engine side motor mount brackets needed.
/6 k-member could be used with adapter mounts. Not sure on the details of a Hemi version. But they are too expensive anyway.
Just make sure you're getting an E-body K-member and not one from a B-body.