Oh my, you struck a nerve!! I just went thru that experience (for the 3rd time). My last two repros did not fit well at all. Perhaps there is more than one manufacturer. I saw a couple repros on cars during my CA trip. The owners said THEY fit OK, but I noticed the flanged area is different than the original valances. The ones I've tried are flanged correctly, but the fit is poor (3/4" too short across, poor contour where they mate to the rear fender). I ended up using my original valance, cutting & splicing the repro's cut outs. Cutting, welding, finishing, painting=$300. (All this for a $40 valance that didn't fit) Good luck.
Neil