I am pretty sure the 210 case uses a 185mm ring gear. A guy on one of the other forums with a c43 built a limited slip with a 190 lsd in his. Also I have looked at the epc on this and have not found a common carrier to the ones that quaife will swap with. I think the only options are the 129/140 case with the qdf5v and the 220 case with the qdf7 or 8v. I know that the early 210 e55 have a different case that the carrier cross references to the qdf5v. I do not remember which case that has off the top of my head.
I think that the 220 case with the qdf8v is going to be the best option for the gears you are looking for. The problem is knowing what to get. Buy a used differential and measure the stock carrier and see if the 8v will fit before you order one though. This is what I did on the 5v for my car. And by all means keep us posted. I may want to go this route if I do not like the 3.06 ratio in my car.