I'd interested in that one too. The example I can think of is the L-89 and L88.
The L-89 was 427/435, aluminum heads and tri-power. Pretty badazz on the street
The L-88 was 427/430 and WAS badazz-- everywhere.
L-71 was 427/435 too, iron heads
L-36 was 427/400 less cam and compression
Probably a bunch of engineers setting around drinking coffee decided how that numbering thing should work. Or the group that came up with the combination went and asked the boss who tossed a dart at a board.