Thanks for the suggestions. The mechanic mentioned something about the octalink system needed for the Claris, his point seemed to be that it is just incompatible with the frame and will not fit, though I have seen that Italian threaded octalink bbs are available. What confuses me the most about this is the fact that he had seen the bike then sent off for the parts, I would've thought that he could have said without trying to fit the parts that there would be an issue.