Boy, this fellow knows his maps.
As I recall, I believe several versions of the '72 map were printed in two styles. One had the route bars on the rear, and one had a blowup of Lower Manhattan/Downtown Brooklyn on the rear.
The conductors used to clip the route bars out of the maps and paste them inside their hats, so with a glance they knew what station to announce as next on the PA system.
IMHO, a stylized and semi-scale version of the '67 map would have been about the best. I never cared for the '72 version (too drab). I always liked one color/one route, dashes and diamonds for rush hours, etc. Thick and thin lines for trunk/branches would have worked too.
FYI: To any Boston types, I know of several old (late 60's) enamel maps, one at Chinatown and one at Orient Heights. Perhaps there are more.......