Here’s how I’d expect it might go. I’m going to assume a J2 DOW because I just can’t get my head around your idea of J1 without taking down the Allied navies.
J1: Buy IC on Shantung, 2TT
Attack:
- Chahar (1inf 1mec 1art),
- Anwhe (7inf 2art),
- Yunnan (2inf 1art 1tb 1ftr 2sb),
- Hunnan (4inf 1art 2tb 2ftr)
2inf 1art 1arm to Kwangsi
Land planes Kwangsi
China1:
Attack Yunnan, land ftr Suiyan
Mobilise in Yunnan, probably leaving 11inf
UK1 Peace:
Buy 1arm 1ftr
NCM 4inf 1art 3AAA to Burma
NCM ftr to India
Land two inf on Sumatra
USSR2: Move Mec Inf to Yunnan
Fly fighter to Amur, Fighter+TB to Yunnan
J2: DOW
Attack Kwangtung from Kiangsi
Attack Philippines
Attack Java
Attack Borneo
Attack Kweichow
Blitz FIC
Attack Yunnan w/6inf 2art 1arm 10ftr 7tb 2sb. Win with 2art 1arm remaining.
The problem is too much has been expended unsuccessfully defending Yunnan.
Alternate - minimal attack on Yunnan China1
4inf 1ftr vs 1inf 1art takes the territory 97%
Leaves 9inf 1ftr in Szechwan
J2: Attack:
Kweichow 7inf 2art 1arm
Yunnan w/5inf 2art planes
FIC 1inf
etc
China2:
9inf 1ftr vs 6units - wins 90%, leaving 4inf
Mobilise 5 inf in Yunnan
UK2 bring in reinforcements
J3: attacking Yunnan:
7inf 2art 1arm 11ftr 8tb 2sb
vs
UK: 6inf 1tb 1ftr 1art 1arm 3AAA
China: 9inf
USSR: 5Mec 1arm 1ftr 1tb
Japan keeps 12 planes if they take the territory, dropping to 8.34 if USSR1 buy includes 3Mec for Stalingrad running straight to Yunnan. Alternatively, let’s say that UK abandons Calcutta to SBR for this turn and the ANZAC plane from Qld also flies in to Yunnan but Japan buys two more SBRs J2. In this alternate scenario, Japan wins 97%, keeping 11.38 planes:

Hmm, assuming this rather maximal Japanese attack on Yunnan, neither strategy quite gets there. Absolute maximum defence on J3 involves buying 3ftr USSR2 in Moscow and flying them to Yunnan USSR3. But that’s more than what is needed. Let’s say you just buy one and also send the other fighter there, with 3mec bought USSR1 in Stalingrad. You could also run the Malaya units up to Yunnan for J3. So max defence is:
UK: 9inf 1tb 3ftr 1art 1arm 3aaa
China: 9inf
USSR: 5mec 1arm 3ftr 1tb
ANZAC: 1inf 1ftr

I’m only suggesting the last one as a thought experiment. It’s clearly not needed.
EDIT: image attachment didn’t work correctly.

