When I did my 7 I got it almost perfect and then polished through the top of it. The Rivithead was really nice. Helping a friend on his 7 right now. DonI suggest that you do it yourself - it can be done in less than half an hour, and achieve a beautiful result. Draw some guide lines on the Van's supplied part, and shape using a bench sander and a Scotchbrite wheel. Polish with fine sandpaper (with wet and dry) and aluminum polish.
Very satisfying way to spend a bit of time!
Bill Brooks
Ottawa Canada
RV-6A finishing