My leaf springs are pretty flat. Any suggestions on where to get a new set that is correct for a 69 A Body with HD springs?

Check out ESPO Springs & Things. They are a sponsor here at this site. They make a great after market leaf spring. Lots of members here will recommend them.

The big question when buying from ESPO is, do you buy stock ride height or +1 or +2 or even -1?
It can be a little crap shoot when it comes to the ride height that you are looking for and what you might end up with.

Rarefish, do you have any other suggestions on where to get them? I'm looking for factory correct height and ride.

I used Eaton Springs because I thought they looked more correct. There is nothing wrong with ESPO springs. Have used before. Eaton Springs Little more correct. I reused the bottom spring that had the part no. on it. Good luck!

I just go to Spring Align and have them re-arched, I don't know if there are shops like that near you...

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.