I would need at least Allies+60 to have an even chance against Adam. He will find that small strategic mistake somewhere on the board and ram it down your throat. A couple expensive units here or there, or a few high-value territories and he now has the advantage as Axis. Furthermore he will never make a big mistake to let you back into a match.
With your additional Allied starting units you will get strong control of a couple theaters of operation on the board (Africa, Russia, Atlantic, Med, India, Money Islands, China, Pacific, Siberia, Middle East), but that still leaves a bunch of other theaters where he can press his strategic advantage to ultimately win late-game victories. Just because the Allies controls Moscow and India on G7 and J7 in a PBEM game doesn’t mean that the Axis can’t create enough threats to prevail. That is a huge difference compared to a face-to-face match where usually one side yolo’s it and gets in a big fight because they have become bored during the many hours of play.
Eventually the Axis mobility will allow Adam to quickly pivot faster than you can foresee, pressing a killer attack while maintaining just enough defense to stall or delay the Allies’ plans. You are celebrating that the stack in Moscow is holding strong and all of a sudden there is sufficient fleet with Luftwaffe support to crush Egypt. You think that the combined forces in the Middle East will provide adequate defense against the Italians+Germans when all of a sudden he gets his Japanese forces to swing the difference in odds. You think that you have appropriate ship blocks in the Pacific and he will bring in German bombers to force your Allied forces to consolidate into a non-strategic sea zone. He will find something and you will lose. Soooo many great people have learned that lesson the hard way. The Axis have control of the momentum and can maintain it throughout the game if the player has sufficient skill and the dice don’t wreck havoc.
