I went to a local spring shop to have the original springs on my 69 GTS re-arched to a stock ride height, but they told me that they could not guarantee the end ride height.
I ended up getting a good deal on a pair of new Mopar Performance HD springs at Carlisle a few years ago. The one problem is that they are biased like SS springs and I ended up with the back end tilt.
I went out and bought one more new driver's side Mopar Performance spring.
So now I running a pair of left side MP springs.

ESPO has a good reputation, but when researching past posts on people who had bought them. I did see where some people said that they wished they had bought the +1's or wished that they had not bought the +1's
It probably splitting hairs a little for some, but you really hope to get it right the first time.