It should be o.k. that really isn't the most reliable psu just so you know.May not be able to put out full rated power above room temperature, and may slightly fail to meet ATX specs. Nevertheless it should work fine.
Any decent enough 600 watt power supply can handle almost any single GPU system. A 760 or 7950 will be be fine on a 600 watt system.
Yes. Than you for clarifying that. When I built my system I was slightly scared that 600 Watts would not suffice. But now, as you said, I'm definitely sure that 600 watts is adequate.