Go ahead although it wouldn't give you best money investment return. Why?
I used to have a P2-350 and Asus P2B in 98. I overclocked the CPU using FSB133 getting 466Mhz. The AGP original transfer speed of 66Mhz is forced to 89Mhz.
FSB100 2/3 get you AGP66
FSB133 2/3 get you AGP89
This forces the graphics card to run out of spec, in short overclock, but thankgood the Riva TNT1 ran perfectly.
So for your case, you should use FSB133, overclock the AGP bus as well, that would make up for the lost of performance from AGP4x over AGP2x. with a AGP89, you are probably seeing AGP2.6x something like that, see toms pervious review.
Best regards
cx5