If it was me, I might try and incorporate a slight javelin fender hump;
http://automotobounce.com/Amc/Amc-ja...ery.html?pic=2
maybe about 30-50% of what was in the later models, along with a full sheet metal stretch to wrap around the tire.
It might give you the ability to have a similar wheel opening front and back.
The spoiler on this page could look better with a little more 'artistic license'
http://www.tajavelin.com/history.html
maybe you could fabricate something along those lines