If your frame has a 68mm English threaded BB shell and your crank is BB30, then you need something like this Threaded to 30mm ABEC-3 BB - Black Which is an English threaded external BB with 30mm ID bearings for your BB30 crank. This is a bit kludgy but realtively cheap. The most elegant solution would be to get a 24mm spindle external bearing crankset and bottom bracket like an FSA Gossamer MegaExo, Shimano 105 Hollowtech II or Raceface X-Type. This leaves you buying the crank and BB but you may be able to sell or trade the BB30 part.

As for the sanity of this exercise, it depends on the quality of the frame. If it is a good grade of steel with nice lugwork and dropouts in good shape, go for it. If it's a cheap frame with stamped dropouts, get it working with minimal investment, or put the 105 stuff on your Raleigh and waterfall the Sora group.