Need an accurate STOCK height spec of a 90 Rx7 Conv and where the measurement is taken from. NO rebuilt suspension please.

I had to rebuild my limited slip in the rear end and after having such easy access to the suspension, I'm upgrading the suspension (any tips?). I forgot to measure the stock height before starting the project. I only want to lower the car 1". I've been told the conv is heavier and sits lower than the hard top, therefore performance suspension lowers my car more than specified (?True?). Thanks for any ideas, your time and info.