Wonder no more, because according to these pics sent back from Eric at SEMA, what you're looking at is the Mallett Solstice V8 with an LS2 6.0L V-8 engine, a.k.a. the 400-hp base engine in the C6 ...
However, if things had gone the way Breckalnd Technologies intended, the Pontiac Solstice would have had a British counterpart called the Beira, which an LS V8 engine would have powered.