Complex sentence: The conversion successfully masked the ship's origins as a freighter, and gave her a modern, well-proportioned, though slightly-boxy profile, in keeping with other passenger vessels designed and built in the late 1950s and early 1960s.
Split into simpler sentences: The conversion successfully masked the ship's origins as a freighter, and gave her a modern, well-proportioned, though slightly-boxy profile. Overall, her appearance was in keeping with other passenger vessels designed and built in the late 1950s and early 1960s.