Wait there's more.
When converting L to CI, I always multiplied the L by 61.023 (a tech manual gave that conversion figure) to determine the CI displacement. In this case 5.7 X 61.023 = 347.831. This is the 347 number you heard about. However, car companies only advertize displacement to the 1/10 of a L, so the conversion won't be exact. Each 1/10 of a L also equals approximately 6 CI so when converting CI back to L then there is some wiggle room to describe the L displacement.
Of note are the old 5.0L engines produced by Olds, Chevy, and Ford. By CI they displaced 307, 305, and 302 CI respectively. Converting them to L by dividing by 61.023 they would more acurately displace 5.031L, 4.998L, and 4.949L. Ford's 302 probably should have been described as a 4.9L but Ford decided to round up (probably for marketing reasons).
Bottom line - I accept 345 as the correct CI displacement for Chrysler's 5.7L engine.