I don't think lower GC would result in a different optimal roll center location - CG is still above the roll center typically used on a high performance chassis. Sway bars would likely get softer for a given grip level.
This is one of the best things I've seen in a long time. I have 3 FD rx7's 1 with a 1jz built by Sound Performance and another with a 2jz that is being sent there for some updates.
Seeing your thread makes me want to revisit the concept of a rotary build in a FD.
Best of luck with your build. I'll be tracking it.
The vertical end plates on your wing can collapse the whole thing if you get sideways at high speed; the wing supports are not triangulated. I would re- think this.