Lots of early Pentium motherboards had VLB slots (just take a look on TH99). There were even ISA only Pentium boards. Most of the VLB Pentiums are probably scrapped by now, but they certainly exist and they work just as well as VLB on a 486.
I've tested several cards on my VLB Pentium, including Mach32, Mach64, ET4000W32P, S3 764, S3 964, S3 968.
The missing chip on the Mach32 is a RAMDAC, though the card still has a RAMDAC just an inferior one. The socket is probably available to upgrade. RAMDAC doesn't affect graphics speed, just the frequencies at which screen resolutions can be displayed. I recommend getting a mach32 with the faster RAMDAC or instead a Mach64 which is much better:
http://cgi.ebay.com/ATI-109-26900-30-MACH64-V … p3286.m20.l1116
"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium