In my opinion put the rear bridge re-design on hold. A lower cost option would be to clone the rear uppers with double ended heim joints (use identical size and brand and materials and make one end LH thread) and add the frame to body gussets and repace the tired / worn bridge bushings. 99.9% of car guys and 99% of car show judges wont know the difference (maybe 6 of us here on this forum may notice...after 10 minutes)
The bridge re-design will definately cost more and stand-out as a modification and I personnaly am not sure you will see a difference.
I have driven over 17,250 km (10,000 miles) not often at low speeds and cannot say I have experienced simutaneaous over under/oversteer as in the original Sports Car Graphic article.