This art of yours is freaking great.
I don't think you need to mimic software rendering. At 64*64, you're going to need all the detail you can get, specially on distant objects, so I'd recommend regular 32-bit rendering with anisotropic filtering and trilinear mipmap filtering.
Since the resolution is so small, you can also use 8-bit alpha channels on the sprites and enable FSAA to smooth out all edges.
And for sharp pixelated texturing on close-ups, you can use this
large texture magnification for pixelated games without aliasing between texels shader.
By combining all these approaches you should get a visual style with sharp texturing and smooth geometry.
Also, pre-render a shadow directly from above the models, to give a better sense of them touching the ground. You can even use an 8-bit alpha channel to make them really smooth.
The fact that the prerendered models aren't lit directly from above isn't a problem. Artistic freedom can be more charming than realism in such cases.