Are you sure your bike doesn't have conventional English BB threading? That would be my bet. Assuming it does have English threading, sourcing a bottom bracket to match the crankset of your choice should be a piece of cake. Honestly, it sounds goofy to me to put on all that nice 105 stuff along with a crappy crank.
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My greatest fear is all of my kids standing around my coffin and talking about "how sensible" dad was.