71 Duster hood hinges w/lightweight springs

Yes, you need the weight and the leverage to close the hinges.

As an example, a Dart Lite or Feather Duster hood uses springs that are in between the tension of standard OEM and aftermarket lightweight versions like you have. But trying to close the lighter Lite or Feather hood with regular springs is more difficult and sometimes tries to bend the hood because the aluminum underside bracing is lighter by 10-15 lbs and not as stiff. (That little weight does make a difference.) But it's still heavier than most glass hoods. I heard that a good mid-range substitute spring is from FWD Daytona, Sundance, etc. and may work for a Lite or Feather hood, for anyone that may need some. But I haven't tried it yet.