74 Duster 4 banger Street/Strip Build

I'm gonna need to do some rocker panel repair this weekend. That gets me thinking on the quarter panels. I was thinking AMD half quarters.....but I also see VFN fiberglass offers fiberglass half quarters. Fiberglass = $380 a pair, AMD = $600 a pair. Fiberglass = light. My main question is....does fiberglass = dependable and no cracking where it meets the old metal? I mean.....I'm not building a show car, but I don't want a Crack in my paint