It is much more complex if you want to get into the nitty gritty details on how the vehicle will handle (from what I read).
The first thing you have to always factor in is where your components will sit within what space you have. What will the links hit, oil pan etc., what will the axles hit, how tall is your ideal ride height, etc. What kind of steering setup are you going to run is another factor, especially if your going to have a draglink.
Second, you have to determine what your ideal ride qualities are within your size / location limitations (see #1). Do the axles steer during articulation or not, what happens when you apply the throttle (stinkbug, or suspension rise), likewise with braking. Vehicle weight and roll center, blah blah, so on and so on.
Third, you have to figure out what strength suspension components you will need for the layout you figured out in #2. Then check prices, determine what you can afford and the revise #2 as necessary.
Fourth, the actual fabrication, concequencial redesign because of some factor you forgot and trying to figure out how to weld to cast iron.
Fun fun, I hear yah on doing it yourself. Still, there are some serious obstacles ahead. Good luck on your project!
P.S. Call S+N, it might just be easier to have them take care of the above. I hear they like Budweiser too. :d1: