Nice work so far, just don't rush to get it in fiberglass as the more time you spend perfecting the clay the better your frp part will be.
This is actually my job (clay modeller at Ford Design) & a few years back I did a wing for my Z32 in clay, check out my build thread for plenty of photos of my process & tools, how I balanced the sides, etc. clicky
As for your design, I'd be bringing that hard edge down a bit so it cuts through the fuel filler cap, looks a bit square / heavy in your second photo looking backwards across the guard.
Great work so far though! Which brand of clay are you working with?
cheers, Tim