I highly recommend LaBelle's roof rounding kits for shaping the roof. You can find them on the website under button 3 parts and accessories. They're easy to use and just takes some good sandpaper (a sanding block helps greatly), and a little patience and you'll have a fine looking roof.
Your call of course whether you want the Labelle roof or MRGS. Enjoy building. I think LaBelle's are fine kits.
