Isn't Oceania's cabinet going to be made from Big Brother and the ministries?
I'd propose:
HoS: Big Brother - Diehard Reformer. Even though he's an elusive figure and probably doesn't exist as a person, BB is the concept of a revolutionary leader who spread out his (soul-crushing) ideology by military conquest and wants to do so for the entire world.
HoG: The Inner Party - Silent Workhorse. The IP is pretty well disguised as just a bunch of supervisors who don't really do anything beyond managing the day to day business of the ministries, it's small and doesn't use up too many resources. While living in comparative luxury, they and their upkeep do not compare to that of the RL high society.
Alternates: Miniplenty - Ambitious union boss, Miniluv - Backroom backstabber, Minitrue - Flamboyant tough guy (propaganda)
Foreign Minister: Big Brother - Ideological Crusader. See above.
Alternates: Miniluv - ironfisted brute, Minipax - general staffer
Armaments Minister: Miniplenty - Military Entrepreneur. Starving the population has its "benefits" stated in the book but if there is still any surplus most of it would go to the military. See above for the Inner Party.
Alternates: Minipax - Battlefleet proponent. Of all the known military technology of Oceania, their floating fortresses stand out as the resource hog.
Chief of Security: Miniluv - Prince of Terror. This one is obvious.
Alternatives: Minitrue - Efficient Sociopath. Obvious again.
I don't know where the Thought Police fits in between these two ministers but I think they were mostly under Miniluv.
Chief of Staff - Minipax - School of Fire Support or of Mass Combat, maybe two separate Minipax "ministers".
Minipax is the most important ministry for the purposes of a wargame, though Miniluv seems to have been the principal one in the book.
Alternates: Miniluv, Big Brother - School of Psychology.
Chief of Army - Minipax - Decisive Battle doctrine. My interpretation of the victory in Africa. Or Elastic Defense.
Chief of Air - Minipax - Army aviation or Carpet Bombing.
Chief of the Navy - Minipax - Power Projection, maybe with an alternative for decisive battle and/or base control.
A lot of breaks from the novel will be necessary for this mod to work.
I say we had Goldstein alive and well and have him sparking revolts in some part of Oceania, like North America.
Also, since 1984 apparently takes place after a nuclear war the IC output of each nation should be low, not to mention the crippling effect of such totalitarianism.
Oceania's unit models would be simply named "Victory [Unit] [Year]" such as Victory Tank 1984.
Probably obvious but
Oceania's anthem should be the lobby music of this mod.
National bonuses: Oceania has more IC than others and is more centralized, Eurasia has more Manpower than others and Eastasia has greater unit Morale and Organization than others.
In HoI2 ideology terms Eurasia is Stalinist, Eastasia is National Socialist and Oceania is Fascist. All are full dictatorships with just changes in left/right scale.
Mostly good ideas, but I have a few nitpicks and completions to make. First, the IC of Oceania at around 500/360 seems fine for a devastated world, considering the territories it holds. Eurasia should be about 240 base IC, Eastasia 150 base IC and the contested areas should be another 50 IC, most of it in India, but damaged to 0 at the start from constantly changing hands and from bombardment.
Also, I think you mixed up Eurasia and Eastasia. China (Eastasia's core domain) is the world's population center, while in WWII, the point of divergence from where the dictatorships emerged, the strongest military traditions were the German and post-Stalingrad the Soviet/Russian, hence Eurasia should have the best quality ground forces and Eastasia should rely on numbers and militia.
Ideologies: IMO Eastasia should be National Socialist, and Eurasia and Oceania both Stalinist. Alternatively all 3 could be Stalinist. Events could shift relationships around in a heavy-handed manner to represent the doublethink based propaganda. "We have always been at war with X."
Adonnus: If you want Australia to appear under Liberate Nation you must remove Oceania cores and claims on it.
If you need any events, scenario manipulation or what have you, tell me here or in a PM and I'll see what I can do (events especially shouldn't be a problem). I barely ever thought of making an 1984 mod but I'll definitely help out in one if I'm wanted.