You could drill and tap 8 holes in the circumference of the BB shell (4 on each side). Then, a sealed bottom bracket unit can be inserted and held in by 8 allen head screws.
I did a conversion like this on a Lambert (the old English bike with press fit sealed BB bearings?). Couldn't find replacement bearings and spindle, so had to adapt the frame to use something obtainable. It then allowed me to install a regular crankset, and I was able to get the bike together and rideable.
As this was done on a classic bike I wouldn't recommend it for every stripped BB job. I really wanted to get the Lambert running, and to prove to myself this kind of adaptation worked. It was a labor of love, took more time than it was probably worth. But it functioned just fine. And only an observant history buff would recognize the modification.