I am curious on the technical side of the implementation of such combo card. I wonder if it uses transparent PCI bridge or standard PCI bridge to split the bus, as the later has a software impact that increments the bus enumeration on the new bus segment. Performance wise, both chips now reside on 1-hop bus segment if you use it on legacy PCI chipsets such as Intel 440BX or 2-hop bus segment on more recent chipsets that demote PCI to the south. A lot of Voodoo1/2 era games rely on low-latency, fast access to Voodoo framebuffer. As for the PCX2, if its peer-to-peer PCI bus mastering traffics would be confine within the PCI bridge on the combo card or it relies on upstream PCI bridge for peer-to-peer traffics. The later would further downgrade the performance of PCX2 rendering into Voodoo3 framebuffer.
I wonder if you would really put it into use on retro PC for games or just shelf it for a show. Otherwise, both chips are at least 20 years old of age and the semiconductor process at the time would at most spec'ed for 10 years of physical material degradation.