Dents in those older rounded fenders are not that difficult to get out even if they look really bad. Hammer + dolly + shrinking disc action would bring them back around.

Better to fix them than buy fiberglass parts that will be wavy and require way more prep time than people realize. Most of the that 'glass stuff does not just bolt on and fall into place. You'll have weird gaps and alignment issues that will need to be addressed too.