Trust me, there's probably few people on here that did more projects that take patience and pre-planning - MPFI, 6-speed swap, Classic auto air, etc... this one just doesn't seem worth the extra effort compared to the other options.
Most of the other frame connectors you just pop the front parking brake cable out, drill a hole a little higher, put it back in and adjust and the rest fits fine, including the fuel and brake lines.
That little bit of extra vertical height and being tied directly to the floor is minor, and the USCT ones are open on the top. I don't know the wall thickness but what you're doing is resisting twist by having a 3D shape with that or a tube. The time for fitting for tolerances and doing about 8x as much welding for minimal to no gain. My friend and I were discussing this for his '71 Demon that he's going to be doing some rally cross with.
I have the USCT inner fender braces (which I might not be able to use due to the big tires) and the torque boxes. Just need to get around to putting them on.