as all of you know, AAG40 involves the additional nations of China, ANZAC, France and Italy in contrast to AA42, where only Germany, England, US, Japan and the Soviet Union are set up on the board.
My question: Are there any rules here available that use the AAG40 map with only the five nations of AA42? That means only German, English, American, Japanes and Soviet troops being placed on the map with no further involvement of the minor powers mentioned above.
No, it would need to be your own invention. At least one other person has taken AA50 setup as a starting point for a 1942 year start setup using AAG1940 and HEAVILY modified it to use all nations including ANZAC, China, France, but to my knowledge no one has removed countries.
AA1942 obviously has a VERY different China role and would probably be the big balance hurdle. The other problem is that the minor powers have inflated economies compared to their values in 1942. By combining Italy in AA40 with Germany it might make way too much of punch for Russia to handle. Likewise, in the pacific, by combining Anzac with Britain (especially if you don't force a split economy that AA1940 uses), you may end up with a UK power that is harder to punch down than the US.
You'd probably need to come up with your own setup (start with AA1942 and then start adding as necessary), and probably some rule adjustment to go along with it.