DDdy bust & torso on Obitsu 60cm?

Is this combination technically possible? I know that DDII busts/torsos can be used on an obi60 with a little modification, but I don't know if the same holds true for DDdy and others(DDS/DDIII/DDdyIII) based on the newer frame. I'm sure that the transition from DDdy hips to Obi60 thighs would be quite ridiculous even if it could work, but maybe, just maybe the additive mods I'll be doing to her legs would make it less jarring..

 

If anything, a DDII shapely bust and torso would work just fine, but if she could have a fuller, curvier figure that would be great. ^^

As you mentioned, the DD2 busts and torsos fit on the Obitsu 60cm. I've had several Obitsu 60cm girls with that arrangement many years ago. It's not really a matter of the internal frames fitting. As you've discovered, it's more a matter of using vinyl exterior parts of the same or similar diameter. The DD2 bust and torso work because they fit together (at the waist) and are of comparable sizes to the other parts (shoulder and hip joints) that connect to them. The DDDy bust to torso area has a much larger diameter than the same DD2 parts, so if you want the DDDy bust you would need to go with the DDDy hips to ease the waist transition. DDDy bodies use the same arms as DD2s so you're good there, but DDDy thighs (as you mention) are larger and hence create sizable gaps at the hip joint.

Additionally you could try replacing the Obitsu thigh vinyls with DDDy thighs. The DD "over lapping" style knee cap may fit completely over the Obitsu 60cm ball joint knees. Removing the joint ball caps of the Obitsu knee joint would make the Obitsu knee joints more like the DD knee joints and might help them fit inside the DD knee vinyl by cutting down the width of the knee joint internals.

Thanks for all the insight as always, K-2! I didn't know that DD(dy) thighs could possibly work on a obi60. That's really interesting, though it won't work on mine since her legs were previously shortened to make her height closer to a 50cm obitsu. ^^" I think I'll stick with DD2 parts and her original legs/arms after all. She'll still look pretty busty compared to the others anyway, which is what I wanted.

If busty is what you're looking for there are a lot of those aftermarket soft busts like the Peach Pai and others. They come in sizes ranging from "wow" to "stupid huge".