Very common to trim/modify GT type fiberglass rockers or valances to fit as all flares are not installed the same.
I did a set of rockers for
@914Boss a month ago. I also just did my rear GT valance (for Chucky) two weeks ago.
Time-consuming, but easy.
You'll need: Fiberglass Resin, mat, Everglass fiberglass filler with fibers, glaze putty, sand paper, etc...
Oscar