Splitting it up into chunks has made this infinitely easier. I've discovered there are 536 to 537 sectors between 213856 and 214392 damaged* by the ring so these are filled with dummy data. One of my attempted reads read the 537th sector, but it didn't pass an ecc/edc check, so not sure if that was a fluke or not yet.
My biggest problem is there are three sectors past the ring that are not passing an ECC/EDC check. Two providing consistent results, but one having two bytes bouncing between two different values.
Because of this and because one of my drives is picking up some extra bytes on a few sectors (unrelated to the previously mentioned three) that breaks the ECC/EDC verification, I'm gonna try getting the disc buffed and attempt these sectors again. I've also purchased a sealed copy off amazon which should get here next week to do comparisons against.