I want to use a reversing ring to attach a Nikon 50mm f/1.8D (52mm filter) lens to a Nikon 70-300mm f/4-5.6D ED (62mm filter) lens. I want to attach them in such a way that the 70-300 is mounted normally on the D80, then face-to-face attachment of the 70-300mm with the 50mm. 

How do I attach a 50mm in reverse manner to a 70-300mm?  

What filter thread do I need to attach to both of these, and what are the pros and cons of this type of attachment?