Re the teaser: Normalized relations with Japan are certainly no bad thing. I think, though, that realistically, reaching such an agreement by 1955 might be a bit too soon for any real rapprochement between the two; it's been less than a decade since the war ended, and there's still plenty of bad blood and high emotions to go around on both sides.
One possible thing working in its favor, though, would be having the United States serving as a third-party mediator between the two, especially if they can get Douglas MacArthur to serve as the mediator in person. He is perhaps the one figure that both sides can actually respect and consider relatively impartial, and in a world where his "push to the Yalu" stance ultimately paid off, his popularity and credibility on the world stage generally are going to be through the roof.
