Those dropouts are not that easy to get on a new bike. I'm struggling with that right now. I don't see how it's really practical to try on an existing bike, especially assuming it has straight stays. It would take some pretty extreme cold setting, which is not that easy on an existing frame. I have seen you mention replacing dropouts a couple of times now, have you done it? Do you have pictures somewhere?

I think the only way to get discs on an existing road bike is to cold set the dropouts to 135 and go with a seat stay mounted tab. There are adjustable tabs for horizontal drops, but as Andy says forward facing drops might have a problem with wheel ejection. Paragon had some vertical dropouts with built in stay mounted tabs, but I'm not sure they still make them. Probably some people out there have some spare ones.

I have a couple of frames that I have thought about replacing the chain stays on. Seems like a silly amount of effort. I might still do it, dunno.