Topic-revival:

I finally mounted the front spoiler on my daily driven '73 Dart;

The sides of the spoiler were cut and modelled to fit the contours of the valance and front fender better.
Currently it's mounted with 6 bolts. Used 2 existing holes in the lower valance. Might want to add 2 more in the valance.

For the time being I'm OK with the looks.