What's going on with my new suspension?

What's going on with my new suspension, cut springs?

I just had new suspension put on my 88 GT (see list below) a couple months ago; it's my daily driver. Now the back end sits a full inch lower than the front! The shop that did my work, work that has always proved reliable in the past, said it would take a few weeks to "level out". But it has actually gotten worse. I've had this car for 14 years and it was always level, if not a bit higher in the back (a look I prefer).
Plus, the car was handling very poorly, alot of side jumping on bumps. The suspension change (plus tie rods, sway bar kit, ball joints, new lower control arms, new Toyo tires and alignment, etc...$3,000 dollars worth of etc.) improved the handling but it's still not right. I have never changed the quad shocks, the originals are probably still on. Do they affect handling?

So the front struts and rear shocks are ATech brand.
The front coil springs are Moog 8600
and the rear coil springs are Moog CC835
I know of, and read a lot about the big name brands like Koni, Eibach, Bilstein, KYB and suppose they are the best brands. Never heard of ATech; heard of Moog but don't know anything about them...don't know anything about springs. I wonder if I should have specified to the garage what equipment I wanted put on the car.

So, what has happened? Is this the wrong equipment for this car? Bad equipment? Or something else?
Thanks, your comments are valued.
Brian

So, the issue would likely be due to the springs, not the shocks/struts?

Then rather than buying new front springs, how about cutting them down? I've read about this being done.

Thanks for the response.
Hm, now I'm wondering...do I need to lower the front or raise the rear??? Are there some standards or guidelines for ride height?