I'm running an 8 spd SRAM cassette with 9 spd Ultegra RD, 10 spd 105 double FD and a 9/10 spd 53/39 crank. No problems. Chain is a Shimano HG50 8 speed.
Of course, YMMV. Some 8 speed chains are narrower than others. Go with a narrower model if you think clearance could be a concern with your crank.