It might be if the specs on the nameplate prove sufficient, and if the PSU is a decent model. Not all PSUs are created equal. Please list the make and model of the PSU.
That is going to be safe enough. Yes, it will work and run. Is your 560 the version that requires a 6-pin connector? Most do not. If not, you should be OK with 2 x 16 amp +12V rails rated for the full 320W.