Tbf, the removal of the roof supports and transfer of the cables to the towers at the north stand end is much more complex and costly than anything involved with the south stand.
There is that. The space available is the same on both sides, because the whole stadium is surrounded by a wide ring path, and both stands sit within that ring. That's before you get anywhere near the road. The 'main' face of the north stand does actually sit 3m back from the main face of the south stand. But the outermost point of the south stand is further back to the ring than the furthest rear face of the north, so it really isn't a space thing.