Here's a set of "before and after pictures" of my chainplates....
This pictured plate is one of twelve that I removed, refinished, polished & inspected on my 38 year old vessel. No cracks, no voids, no discernable problems,- there's a great variety in quality of materials. I undertook this task because I was getting some light
hull streaks from the mild surface rust, but no structural problems. Don't discount the possibility that old quality chainplates might still perform well. 'take care and joy, Aythya crew