Question about spring rates and ride height

[Nikwho]

So, I am looking to put new springs on my '67 Pontiac Tempest. The Pro-kit from Eibach lowers the front 1.3" with a spring static height of 362.4mm with a spring rate of 550lbs.
I have a brand new set of Eibach springs that were a 1" drop spring for a 70-81 F-body. The static height on these springs a re 352.1mm with a spring rate of 577lbs.
So, the springs are about 10mm shorter and the spring rate is 27lbs stiffer. I am wondering how the ride quality and ride height will differ between the two.
I would like to get away with running what I have as opposed to buying new springs. And, the springs that I have are brand new and seem very similar.

What do you guys think?

The camaro springs are 10.3mm shorter, which comes out to just under one half of an inch shorter (1mm = 0.039 inch). I am wondering the difference in ride quality going from a 550lb spring rate to 577lb.

Does anyone know the spring rate of the factory springs?

I am not trying to be cheap by any means! I was just thinking that if the new in box Eibach springs that I have will work well, I may as well run them. Any speculations on how the ride height may differ?