I used ATIFLASH with ATI.7000.32.Hyundai_010213.rom which had the same device ID as mine (5159) and it's now correctly recognized on bootup and by Windows as a Radeon 7000 PCI. The BIOS model information and the warning from the flash tool suggests that it should be seen as only 32MB but it appears to recognize and work correctly at 64MB (which it actually has).

You flashed the AGP ROM on a PCI card and it worked?

Apparently. This was three years ago so I can't recall the actual event.

I think more important than the size of VRAM is speed. I have a 32MB SDR BIOS that will not work on a 32MB DDR card, but a 64MB DDR BIOS will work. I am confused on if there was ever an SDR VRAM Radeon 7000 released, but I've seen BIOS for them. Here are 2 BIOS which I've found for Radeon 7000 / VE (RV100).