Well, that would be up to the supported drivers in the OS. You might have to ask Oracle support if they have such a list.
With a PCIe slot, I would guess anything up to about the Quadro 4000 series would still function in there. The newer cards might be looking for a UEFI BIOS.
FX 5500 was a G71 GPU, so something like a G92 / G92b / G96 GPU might work, that would be something like a GTS 250 or Quadro FX580, FX380.