I'm not sure if you already decided on the video card.
The i740 would do nicer filtering than the Riva 128 so you'd get better image quality. It is less common though so you might run into more compatibility problems than with the Riva 128 which was the fastest Direct3D card for a while so it was tested quite thoroughly in that period. If you don't already have an i740 it might be somewhat hard to get.
Regarding the performance: Vintage3D (Putas' site) doesn't really contradict old reviews about i740. Most reviews are from when the chip came out so possibly immature drivers where used. Additionally the chip relied on AGP texturing so it will slow down a slower system even more.
About the G200: I think that would be a good choice: Excellent image quality/sharpness in general, good filtering for 3D, 16MB RAM option, good performance, low power consumption, drivers available for other operating systems (Win31, NT 3.5/4.0, W2k, XP).
Just had a look at http://www.vgamuseum.info/index.php/history-tree for other options:
Rendition Verité V2200 (proprietary API, slower, 1997, possible hard to get)
S3 Savage3D (proprietary API, mainly for Unreal though)
Banshee and TNT were already mentioned.