The New Yorker grill will fit a Newport as a complete unit including headlight mounting frames, headlight bucket, surrounds and glass.---- But - the outer sections must be replaced completely if you want to use the outer sections (headlight mounting hardware ect.. from a New Yorker or 300 on a Newport grill center section. The outer portions are just different enough where headlight hardware won't interchange between a Newport and the other models without modification.
My car is a Newport/New Yorker hybrid.. It has the Newport Grill with New Yorker headlight sections.