McCain SchmCain (w/ poll)

I happened upon this http://www.mirror.co.uk/news/allnews/tm_objectid=14285582&method=full&siteid=50143&headl ine=dubya-is-trailing-8-points-name_page.html article. When I got to the line about a Kerry-McCain ticket adding 6 points to a Kerry lead already at +8 over Bush/Cheney I really got to thinking. Since McCain has stated repeatedly that he has zero interest in being someone else's Vice President, and since I take him at his word, what if Kerry were to find some other Republican with which to run in order to shore up the moderate & disillusioned conservative/libertarian voters?

So if McCain were to decline the invitation what other Republicans would be as effective in appealing to moderate swing voters and Rockefeller Republican types? Could anybody give Kerry the "McCain Effect" besides the real thing? Would picking a moderate Republican do more harm than good by perhaps fueling cries of flip floppiness on Kerry's part?