Afraid I'm not bringing much to the party answer-wise 🙁 as my installation went without a hitch.
Again, stuck to minimal kit so board, 3 x 128MB PC133, P3 500/512, TNT2 M64 and basic 98SE install. Didn't install graphics drivers and went straight to the audio package from @chinny22 which worked fine (Gameport, Legacy & PCI).
Ran PCILIST and oddly my Subsystem ID was different, 5345h, and was shared on IRQ9 (with USB). Then I booted from the Yamaha Diagnostics DOS floppy to check the settings & sound tests which all worked OK, and which also confirmed the Subsystem ID as 5345h.
As mentioned, my board is AA 722394-112 Rev A01 with the latest A11 bios - here's a pic of the board and audio ICs
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