Which body for best performance?

If I were to chose a Mopar go-fast body..... for a small block car, an early 2dr post dart or valiant.
For a big block car, id chose a 67-69 2dr post Valiant.
Light makes right. And I've always preferred post cars to hardtops, for street cars or race cars.
I was gonna put a stroker big block in my 67 barracuda notch.... but I'm beginning to think a 408 might be a better choice.