[strictlypersonl]

The GM-style torque arm makes for an elegant design but the short length makes for too much anti-squat unless you can place the front mount very low and as far forward as possible.

IMHO, the most important factor when optimizing a solid axle for handling is keeping the roll center low and stable.
Something I did a long, long time ago on a race car, that I haven't seen done again: A Watts link attached to the bottom of the differential, pivoting in a horizontal plane. The roll center was about 5" high. It worked amazingly well.

The layout of the GT and Cobra uprights were similar but they were completely different pieces. The geometry between the two cars was pretty close though, in spite of the different layout of the trailing arms. In both, the top arm (or its equivalent) was close to horizontal, with the lower assembly slanting up at about 6 degrees, probably for anti-squat/lift.