Yes I did Don. Pretty easy. I never fiberglassed before and it turned out well. I used 3 layers of matting about 4 feet wide on the back side and just filled the front.
The fit of the spoiler was not exactly perfect (not due to my putting it back together). The outside edges didn't sit flush with the lower fender (pictured). And the front curved outer edges of the original metal spoiler (if you can call it that) hit the inside of the fiberglass spoiler. That needed a little tweaking.
I made the aluminum brackets that you see in the pics to keep the front edge pushed down and to keep it from vibrating. They are just wedged into the front lip of the fiberglass, and should bend pretty easily if I hit something.
I'm happy with the looks even if its not perfect. I'm sure it could be made to look better but it's good for me. I've gotten alot of compliments on the looks.
Craig '75 2.0 FHC