Tamiya also made a 1:100 version of this helo as well, and from what I have seen it got good reviews.
My grandfather worked for Sikorsky as an electrician, he helped to build these monsters. I know that they also were able to carry a special cargo box, and when equipped, it was tight up against the fuselage so that you couldnt see the hook assembly. That might also be an option for you if you want to do something a little more different, as these were normally used to carry cargo on the hook instead of the box. Here is a link on that Tamiya kit, click on the pic of the box and you can see what the parts trees all look like.
http://www.armorama.com/modules.php?op=modload&name=Reviews&file=index&req=showcontent&id=3697