Actually your original image size was okay. A slight variance above or below won't make for ginormous images in the sig. Your edited image size is okay as well.
For example, if you look at my sig, the image is short in height, but actually a bit long. But, it doesn't overwhelm the signature area.
As we've both said, if you use common sense in constructing your siggy, it shouldn't be a problem. If it's too big, trust me, I or someone else will let you know.