Billy,
I have been down this road several times, so pleeeeeeeeze, listen. It'll save you money in the long run.
1. It's hard to find the Rancho springs these days. They actually stopped manufacturing them a while ago. That's ok though. THEY SUCK. You will get a nice lift/stance with them, but as stated, the ride is terrible. It's like sitting on a tree trunk over pot holes. You will regret it.
You can have springs made, but it's expensive and YOU have to do all the measuring. This is not as easy as it sounds. You cannot just measure from hole to hole.
Get springs from a reputable WILLYS restoration shop.
DO NOT buy springs over the internet. Trust me on this one.
DO NOT perform a spring over axle lift either. It's easy, with a steering arm modification, but Don't DO IT.
Walcks has springs to fit your application, but I have heard of complaints from folks that received the wrong ones and had to go through it all twice.
Willys America will make your springs for you. They don't keep springs in stock just to pull them off of a shelf. Paul actually makes them for your application. If you want a bit of a lift, he'll do that too. I had it done for my wagon. He built in a 2" lift for me. It's one of the smartest things I've done.
I like that you say you are a bit of a purist. I am as well. I played the game of modifications, but Pure Willys is the way to go. The only thing different on my springs is the addition of Con-fer shackles up front. Willys vehicles have a bit of a forward slope to them that I don't care for, so I put the Con-fer 2" shackles up front to level it out. They don't change the geometry at that measurement.
As far as adding lift with your current springs...You can't, unless you go over the top, or add insanely tall shackles which will screw everything up. You could do a body lift, but that's purely up to you.
Call Willys America and tell him what you want. Then save some pennies to do it right which means you'll do it right and save some pennies.
Steve