Convert 67 to 68/ later tank straps?

I have thought about doing this on my 67 fb barracuda. When I replaced the trunk floor, the donor was a later dart. The anchors are a couple of tabs on the bottom of the spare tire area. But i am not sure where the other side of the strap goes. I will be watching this one:happy1::happy1:

oh pic of the anchor point:

http://1967barracuda.shutterfly.com/pictures/146#148