SuperDave,
It seems like I post this photo a lot, but I guess it's time to do it again....
This is a dirt-simple setup.... a set of Alcan front springs (~240 Lbs/in rate) and a set of STOCK '89 Rear K5 springs on an ORD shackleflip.
The truck rides soft (almost TOO soft) and as you can see it flexes like mad... the real limiting factor is going to be how much shock travel you have, since the springs will be able to give you a LOT more flex than an normal shock will allow. In these photos I'm running a 12" travel shock on all 4 corners.
If I were you, I'd go with a 4" front / rear shackleflip (stock spring) and see where you're at. The rear springs won't cost you anything to try and then you'll know how far off you are from the stance you want. You could do an ORD Zero-rate if you are a bit low, or a 2" lift spring if you really need to get the rear up to match the front.
My point is that the shackleflip is probably going to be part of whatever solution you choose if you want a softer ride, so you might as well install that first before you buy some rear springs you might not need/want. There's not really much you can do up front to fine-tune the lift...once you install the 4" springs, you'll get what you get. The rear is where you can make adjustments with longer shackles, zero-rates or even a 2" springs to get things dialed-in.
BTW- A longer rear shackle is pretty easy to build and you can easily get 1" of extra lift with a 2" longer shackle. I've got some photos of that modification in my gallery photos if you want to check it out.
