I don't think I follow JSCs logic at all. I would put both cards at no more then 40A together. If that 750W has 60A total, there is no way the rest of the machine will use the other 20. So why is it bad to use the 750W? Any quality 60A PSU should be fine.
Will you be running one of the 125W+ chips? Even overclocked except for those 125W chips your only looking at 10/11A. Thats still only 50A, and if you can find something to max out both the CPU AND both cards.
What I'm trying to say is even if you are overclocking your CPU, you still won't hit the wall of your PSU. You would have to have one of the most power hungry CPUs (125/130W), overclock it, and then find a way to 100% load the CPU and GPUs to hit the limit of the PSU. Even gaming shouldn't do this.