Shimano 600 brake pad alignment
 

One of the brake pads is really off meaning that the front of the pad is further from the rim than the back part. The other brake pad is fine. There doesn't seem to be any way to adjust the angle, only a nut that you can loosen to move it up or down. Any help please?

Make sure the brake pad is oriented in the right direction. They are made to be closer at the front than the rear.

No they're not.

If it's the old 600 series single pivot calipers you can either

1) Buy cartridge type brake shoes + pads that allow orbital adjustment (e.g toe in)
2) Bend the arm itself with the appropriate park tool or a crescent wrench to acheive toe in