Electric VS standard fan

I need to do something with my cooling system to keep up during the hottest days of the summer. Im running an earlier 22inch 340 radiator on my 74 duster 360. Just doesn't seem to be keeping up. I have one of those plastic flex fans, that seem to pull quite a bit of air through but maybe not enough. Will an electric setup be more efficient? Im not worried about losing a little bit of power by running a strait driven fan but if an electric fan setup will pull more CFM through...... whats the opinions out there?