For a primary video adapter, It depends on which expansion slot type (AGP or PCI) you'll be using.

My personal list of (sort-of) period-correct primary AGP/PCI video cards I'd recommend for such a system:
- nVidia Riva 128/TNT/TNT2
- ATI Rage II/Pro
- S3 Trio3D, Savage 3D/4
- Matrox Mystique, G200

or for primary PCI-only adapters:
- ATI Mach64/Rage 1
- S3 Trio64, ViRGE
- Matrox Millennium

for a separate 3D accelerator, a 3DFX Voodoo1 or 2 should be fine for a period-correct Glide setup, not sure about Voodoo3 since I have no experience with this sort of stuff, there are also PowerVR accelerators if you're interested in games that use that rendering system.

I didn't exactly grow up in this era so I'm sorry if this seems vague in some way, I mainly depend on internet research for past knowledge.

Don't need much to max that out though people often ended up using a TNT2 as they were cheaper than potato chips but now days it is whatever most can find without spending a heap or whatever is on hand. I've done pentium mmx builds with a voodoo 3 and the card is bottle necked too much so I recommend either a v1 or a single v2 for glide.

As for overclocking you can beat around the bush near or at 300mhz while for the tillamook can go for the moon but most boards will not enable the L2 cache.

Yeah the tillamook can be buggy with some boards.
The problem I have is I don't know how well a overclocked tillamook can preform. I herd they can out do most 6k-2's once you get around 350mhz, but I don't know.

If it was a 233mhz Pentium I got straight for a voodoo1 and rage or Mystique, but the Tillamook part throws everything off for me.
Id thought a voodoo3 would be nice as I could use higher screen resolutions. But now that I think of is a banshee would probably be a better match.

The Tillamook is still just a pentium mmx.... a voodoo1 will scale up to p2-350 or so.

I would still choose a voodoo1 for a Tillamook.