The HD8760 appears to be a rebadged HD7770 so should have the same performance.
The CPU will also affect things and AMD CPU's all bottleneck compared to a good Intel CPU.
So I doubt you'd get 60FPS on "HIGH" but if the CPU is okay and you tweak the settings you'll have a good experience. I don't recommend any texture packs, possibly not even the official HD texture pack.
I had an HD5870 and a good CPU (i7-860) and the HD texture pack with no other mods dropped me below 60FPS all the time though I had everything else at MAX quality at 1920x1080.
(The game is also quite playable at 1600x900 if you need to raise the frame rate a bit.)