During the war, the RAAf flew BMF B-24s. What about a RAAF B-32 in similar scheme?
Perhaps powered by W3420s with R3350s reserved for B-29s?
A couple other thoughts, war in Pacific extended due to delayed development of atomic bomb (perhaps they choose and stuck with the least efficient refining process, the opposite of Benford's
The Berlin Project where the most efficient process was chosen from the beginning and the first bomb was dropped on Berlin as Operation Overlord hit the beaches). This could see the
Alaska-class battlecruisers (
Alaska,
Hawaiii, and
Guam) serving in the Pacific; we might also see the completion of the final
Iowa-class ships,
Kentucky and
Illionis, for that service as well as the completion of more
Midway-class carriers (several were cancelled after VJ-day).
On the Japanese side, one might see J7W2 and R2Y2 jet aircraft and, if some accounts are to be believed, Japanese nuclear weapons (might see the G10N1 built to deliver same or some interesting cruise missiles to be launched from
I400-class submarines).