You should NOT add up US/UK AND SU starting income.
When the US at least joins in Germany/Italy should have chewed a bit of this money away.
Lets assumne the US has … 10/50 income (peace/war),
UK 30 and SU also 30
If Germany starts at 25 and italy at 10.
That would be 70-35 at the start of the game (US peace Russia also peace - full production?)
Germany should Grab up 10 from france during turn 1 (maybe 2) = End 1940
then its 70-45
Add 5 (at least) from Minor axis (Romania, Hungary, Finland etc), we go to
70-50
Say Turn 3 Germany attacks Russia/balkans (Summer 1941) - this initial assault should (with Italians in Africa) take 10-15 points away from the Allies
Then it would be
55-65! - Axis advantage
Even if the US joins in on turn 4 with full income (production should be 1 turn LATER) - Germany/Italy should take at least another 10 points from the Allies
its
85 (55-10+40) - 75! minor Axis disadvantage, but a good player should be still have an light unit advantage…
Thats why I assume Germany somewhere in the mid 20s with starting income (if Russia/UK start with MUCH more than assumed, I would add a bit - but then the initial assaults should also yield more points for the Axis taken from the Allies)