.
...when I converted mine, I had to do a little grinding in the BB shell to open it up enough for the conversion unit to fit where the cups came out. Mostly at the weld in the shell, which did not appear to be cast, rather formed and welded. I'm not 100% certain that the cups I took out with the Ashtabula crank would now fit tightly enough in the shell to convert it back, but it's possible they would.

All you can do is try, really, and see if it works.