Leveling jack stands

I'm going to have my chassis stripped down in a few weeks, and will be prepping it for some modification (to fit v8 and seam welding). I want to make sure to get the car exactly level before having any welding done to it (garage floor is uneven). I thought about just using my jack stands and shimming them with wood blocks or scraps. I got to looking online and found these:

http://www.walmart.com/ip/Camco-Stack-Jacks/14504363

http://i.walmartimages.com/i/p/00/01...60_500X500.jpg

They're used to stabilize RV's and are rated to 6000lbs each, and I think will help me precisely get the chassis on a level footing. They have a warning on them that they are for stabilizing, not lifting. I'm thinking that means "don't twist the threaded rod with a load on it". I'll use jacks and other jack stands in conjunction with them to keep the chassis supported, just in case.

What do you guys think?

Those will be outstanding! Good find.

How are you going to determine if the car is level, or will that matter? Do you just need a firm support?

I'd think you could use a long level on the pinch weld to get the F-R level. I'm sure there are a couple of surfaces front and rear that can be used to find side-to-side level. Good point, though.

Just sit in the car and hold the level.

I was thinking about running a long level down and across the frame rails.