Stock suspension height on my 240Z

Hello, I have fuly restored stock 240Z, but I cannot level my at correct original height. I have stock 240Z springs (35 years old) in front, with new shocks, and 1 turn-cut 280Z spring with new bushings in back. My back always sugs by 1/2 to 3/4 inch) and R&L are not even. I want to get Euro Competition coils or NOS stock coils. But thoese are imposible to find. Should I install Eibach springs with 280Z Insulator in back? or Eibach for 280Z?

I just bought set of 240Z new insulators F&R from Motorsports, just in case I find new stock springs.....Please advise! Jay