Looking great with those flares :thumbs:
3M 8116 is by far the best glue I've ever used. Among other stuff I used it for my front flares and to glue my doorskins to the door frames - on the flares I hit the mating surfaces with 40 or 60 grit, then applied the glue ... These pieces will never come apart.
Your body is a 71??? That's fiberglass and not SMC as far as I know. Kitty hair will do a great job on gouges, for filler I used the "gold" Bondo brand with good results but I keep hearing so many bragging about Evercoat Rage filler that I'll try that next .... Curiousity ....
But yes, get all that old paint off, then kitty hair, filler, then epoxy ....