jermil - you will definately have to run exensions, as stock length arms will land right where your mount is. i know the extens from rock equipment were 12", and based on where my stock ones are (DUSTIN) to the tranny xmember, it seems to be about 17" so I think you would be OK. I am actually looking at custom tubulars with heims on them.
I agree that the tube on 2x2 looks noce, but i dont have a tube bender, so it is flat 2x4 for me, which is what Bill, Don and Dave run and it works well.
I am concerned about only having two mounting locations on your dave. Don had three on his (IIRC) and the ends were bending up becuase they were unsupported. ih8jeeps has the market on end support so far. nice job.
Mark, I was metal shopping yesterday. 6" channel wont be enugh, the frame is more like 7, and more than likely you will have to rip down one side, unless you want it wider than the frame on the underside. Also, take another look, but you will have a hard time getting to the top of the frame, cause enless I am nuts, Dave isnt running a BL is he