As we seem to be rebuilding the nose in addition to adding underpaneling, this is what I would do:
Front-End Radius
The red dots show the front clip/underbody panel while the green dots show the front-wheel splitter.
Raise the stagnation point a bit and place it where it will be most useful (i.e. radiator opening). Front wheel splitters will lower drag due to the yaw-angle of air flowing under the car. The same idea can be seen on the UFE III and Loremo LS
UFE III Rounded Front + Wheel Splitter
Loremo LS Wheel Splitter
You'll see the biggest effect if you add a diffuser on the rear, build sideskirts, and make things out of fiberglass so they can be
smooth. I think I'm getting a bit over the top, but aerodynamics is a package deal...
- LostCause