I have played a few games with the added units for the allies and still find it very hard for the allies to win.
Our group added one more soviet infantry in Soviet far east and moved one of the infantry in Siberia to Urals.
Our version of the Non-Aggression pact was changed to:
The USSR may attack Japan only if Germany has been reduced to holding territories worth a combined 5 IPCs or less.
Japan may attack the USSR only if the USSR has been reduced to holding territories worth a combined 4 IPCs or less.