Doing a /6 conversion to a former Cali car with "very little rust". Well I started digging and opened up the hell hole area and while it's not too bad I am cutting out a few sections and welding in new metal.

Question: The innermost sections of the longs are "C" sections welded at the bottom and open at the top. How could it hurt if when patching we join the uppermost portions of the inner "C"?

Pictures?

I have a few in my email, can someone assist getting them into the world?

thanks

Sure.
I’ll send you a PM.

Sean

Won’t hurt anything but is basically needless weight added for almost zero gain in stiffness.

That was my first thought, the area I am speaking of is in the horizontal plane. Thanks

Correct - the box section is much taller than it is wide - this makes it resistant to vertical bending. The box section makes it resistant to torsional twist and lateral loading.

Adding another thickness of metal in the horizontal plane will gain very little.