I have had good results with the POR-15 system. I used their fiberglass mat along with the POR-15 paint to patch some pinholes in the trunk of my '71 Imperial and was pleased with the results. I think POR-15 probably works best on metal that is not going to be easily visible, such as
trunks and panels under the car (based on the relative difficulty of topcoating or painting over POR-15). The Eastwood product will likely yield better results for body panels that will be painted and viewable.
Best luck! Catch it now, because it will only get worse over time.