There is an A&A game with similar rules. Axis & Allies Europe (the original one, not the Europe 1940 games) gave Germany 12 IPCs at the very beginning of the game, to spend as Germany saw fit. Then the Allied powers were given 12 IPCs to spend as the Allies saw fit. Then the rest of the game commenced.
So, I would guess you are suggested something like that for G40, with an Allied bid to go on top of the extra Allied money. If I were to do something like that, I would have the Allies go first, then the Axis, then the Allied bid. It would make for a wild setup, that’s for sure.
-Midnight_Reaper