Actually, the 57th-6th station was the last to use the style of 1930’s variation IND typesetting anywhere in the station; it must’ve been done around the same time as the extensions of the IRT Seventh Avenue stations between Franklin and 34th Streets, from what I can see, while the Grand Street station (which opened Nov. 26, 1967) had the same type of design idea (circa 1962) as not only the express platform of the 59th-Lex station, but also many Lexington Avenue extensions (including Brooklyn Bridge-Worth Street before the rebuilding job).
That 1974 map, which was the last to feature the EE and K lines, was actually the second variation of the 1972 design. The first variation was used in the first two versions of the map (the first with the QJ, KK and E route to Far Rockaway and the second with the J and K); the second variation began in ’74, and was updated in 1976, ’77 (the last to use Pantone PMS colors for the multi-colored routes) and ’78 (which used 4-color printing and was the last with the 1967-era route coloring).