Complex sentence: The Morses originally housed their Dalí collection in a specially-built wing of Reynolds Morse's engineering firm in Beachwood, Ohio, but the size of their collection--both in number and dimensions--outgrew the facilities.
Split into simpler sentences: The Morses originally housed their Dalí collection in a specially-built wing of Reynolds Morse's engineering firm in Beachwood, Ohio. However, the size of their collection--both in number and dimensions--outgrew the facilities.