PRS 505 UK based, new ereader owner who really enjoys the device

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I have been frustrated at the lack of apparent forethought or planning given to Sony's UK site, Waterstones ie the quantity and quality of ebooks that just are not available yet.
A few days ago I found Books on Board, and was amazed to find the books I wanted in 'ereader' format. At the checkout I was disappointed to notice they are for the US version PRS 500.
Q. Will Calibre transfer the 500 files to 505 files? If not will Calibre convert Adobe Epub, Mobipocket (PX) or Microsoft reader(?) to the 505 format?
Great system Kovid.

(I did search but could not find the answer in the FAQ or history)