I actually have a small stack of Radeon 7000 64MB PCI cards in my basement, capable of driving two displays at (at least) 1920x1080 (up to 2048x1536, I believe).

I used them in Power Macintosh 9600s running (IIRC) System 7.6.

ATI never released a 64MB Mac version of the card — I bought the PC version, desoldered and replaced the flash chip with one large enough for the Mac-compatible firmware, and reflashed them.