FYI - noticed body work in these areas. Added these on mine to stiffen, never liked how much the metal flexed. Make sure the fit is matched before tightening down, read a post once where guy saw it distorted metals when he tightened it down door handle. No telling if it was an issue with his sheet metal or the plate.
Door handles:
Dynamic Renovation - 67-76 A-body Door Handle Reinforcement Plates
Repair plates for striker area with thicker metal:
Dynamic Renovation - 67-76 A-body Driver Side Door Jamb Repair Plate
Dynamic Renovation - 67-76 A-body Passenger Side Door Jamb Repair Plate
Plate for mirrors:
Dynamic Renovation - Mirror Plate Drivers Side 66-70 B-body & 67-9 Cuda
Dynamic Renovation - Mirror Plate Pass. Side 66-70 B-Body & 67-9 Cuda