Basically just turn all of this off. That'll match the original software renderer.If I want to keep the closest "software mode" visual experience, but with the updated models, the interpolation and the 4K, what should I disable?
Fog looks very nice so I could keep that as well.
I already have ambient occlusion off.
Note that there's some slight confusion with Dynamic Shadows. Turning that off only affects non-static lights, such as projectiles. It does not affect static map lights, the ones your find in Dimensions of the Machine. That is intentional.