Z notching frame

I have a 1998 standard cab taco. I just recently had a reputableshop bag it. My front crossmember is way low on my truck, so when it's layed out the front sits about 1" higher than the rear. so they told me that I need to Z my frame. I need feedback on this mod. When done correctly is this safe for a daily driver. They want $1,000.00 to do it, they told me it will probably take about a week to do. Is this a good deal? Keep in mind that this shop does excellent work. What exeactly is involved in this mod?