Well, I converted my 87 Diplomat from the 10.87 discs, like your stockers, to the 11.75" discs. I also converted to the 11" cop drum setup in the back at the same time. Did it stop better? Yes. But it isn't exactly an apples oranges comparison and I got all my parts out of the boneyard so the costs were minimal for the improvement. But I liked it so much I put the same setup on my Cuda, again boneyard donors so cost was minimal.

If I had to buy new, including adapters, I'd still do it.