Batch Change Crop Ratio Only?

I just went through a whole folder full of images cropping them to focus on the subject. When nearly done, I realized that all along I'd been cropping to a 5x7 ratio instead of the 4x6 ratio I'm supposed to use. Is there any way I can lift/stamp this change? The lift/stamp tool applies the absolute x/y crop dimensions from one picture to the next, but I just want it to change the ratio, not the actual position or size of the crop rectangle. Am I out of luck here?