Yep, I also had that "camber change" on that side just like you mentioned. I didn't do anything to fix that, but here's what I did to the arch thing:
First, yep, all eight of the little ears touched. At the time I started all this mess, I had removed both crossmembers from the back of the frame - the rear one and the one in front of the gas tank - so all I had was the two frame rails connected by the front crossmember. This let the frame fall down into good alignment so that all the spring hangers were touching at the same time. It also turns out that both frame rails were parallel to the ground so I didn't have to do anything special to get it level.
Earlier in the process I had plated all four sides of each frame rail with 3/16" plate from the very back up to just forward of the curve where the rails make the first turn in. I then used 3/16" plate just on the inside and outside of each rail from that point all the way to the front (almost all the way to the front on the inside - I stopped under the shock mounts). My frame had severe rust damage and could have been a write-off, but I thought it would be fun to fix it - now it's as strong as an F-350.
When deciding where to make my cut, I measured carefully at many points beginning at the straight middle area and progressing all the way to the rear end of each rail (every two-three inches or so) - I measured from the floor to the top of the frame on both sides. I compared left and right sides and found that for awhile the numbers were the same. However, about eight inches up one arch, or about eight inches from where the rail changes from straight to curved, I found that the numbers began to deviate - one side was moving away from the floor faster than the other side.
At that point I made a cut all the way through the top and both sides of the higher rail (didn't cut the bottom). Gravity then pulled it down so that both ends were now the same distance from the floor. Once the bend was made, all those other measurements became almost the same from left to right, meaning that there had been a difference in the radius of the arches on each side.
Once the higher rail was bent down, all the curves matched and the ends of my frame were the same - presumably my Jeep will now sit level. I was then left with one frame rail with a quarter inch wide cut in the top, and a pie-shaped cut all the way from top to bottom on both sides. I put some round rod behind each cut to support the weld, chamfered each edge in a big way, then butt-welded all three sides.
With the 3/16" plate on all four sides that I had previously installed, plus whatever remained of the original frame also being included in the weld, I imagine this would be plenty strong enough. But just to be sure, I made 1/8" plates about 6-7" wide to go over all three repairs, plus the uncut bottom side. I thoroughly plug welded these, as well as edge-welding them. I have no doubt that the frame will break somewhere else before it breaks in this area, but I think it will have to be run over by a tank before anything happens.
To decide if the high rail need lowered or the low rail needed raised, I checked the frame measurements listed here and there (with some of the numbers corrected by Forum members) and picked which rail was the one that was off from specification - it ended up being the high rail for me (can't remember if it was left or right).
I also checked many, many times throughout the process for frame squareness and proper frame width at all locations - sometimes I had to put the Hi-Lift in there to move something before welding.
Right now, except for some cosmetic stuff, my frame is very sqare and level, and it's way stronger than it was before. Hope this helps! Holler at me if you want some pictures - I took a bunch of 'em!