I also saw this car in person when Hoover owned it, at a Datsun show in Sunnyvale or Palo Alto (I can't remember where anymore!), but I DO remember the car distinctly: the larger spoiler does balance out the looks of the car, while the "whale tail" is almost vestigial in appearance.
You could combine the looks of the two spoilers and have a third, more aggressive whale tail made that came out a bit further from the back with some flat black accents, ala extreme Porsche body kits for '80s 911s. It would look rather hot
By the way, your attention to detail in the restoration is excellent--the car looks even better and 'cleaner' now than when I saw it before.
EDIT: I never read the second page in the thread--you've already got it covered...
Davy