Sorry Steve, I only answered half your question. As far as the tubing, I just buy DOM locally and cut it to length and tap it myself. I'm not a chrome person, so the stainless sounds like a good idea. We all know you have a bad-*ss shop and kick-*ss skills, so you should be able to do it easy enough.
Tip: I know it doesn't apply in this case with your four-bar setup, but if you make anything in stainless that you want polished later, and you need to do some welding on it, finish machining and polishing all your parts before you weld. Be careful when you weld not to scratch anything, and then when you're done, it's easy to touch up polish the welded areas. You can use soft aluminum pads for clamping without damaging the finish. An assembly is always harder to polish than individual parts.
RPM has presented an interesting idea. I've heard of using the ceramic coatings for parts other than headers before. I have to admit, the radius rods he shows look pretty good.
David