As I wanted all my big images to be the same size and have the smaller one as close to the same size as possible (as all the grids are different size the only way to get them exact same size would be to re do all the grids.)
I first cropped out the large white border on each of the images, leaving a small on that fit with the space that was left in between the images.
I then looked at my image size. I unlinked the width and height to change the resolution to 300, as I need a high resolution. Once the resolution was changed I linked the width and height back together. Making sure the units were in inches I made either the width or height fit perfectly with the correct 6×4. If there it didn’t fit the 6×4 perfectly it didn’t matter, this just allows the images to be printed the same size.
After the image was the right size I dragged it into a new blank image that was the correct 6×4 dimensions, with a 300 resolution.
I know that the images will have some excess white border but after they are printed I will trim them to have the small border I want.