This has been a good one to read
My opinions for the OP:
A SOA conversion, and all of the accompanying upgrades to make the SOA conversion worthwhile, cannot be done inexpensively unless you have all of the parts on hand already.
- For example, shortly after the SOA conversion on my truck, I needed new tires which prompted new wheels. The added flex prompted lockers and steering system needed to be upgraded to push the bigger tires. Next thing was that the inner axle shafts needed to be upgraded to handle the bigger tires, and the list grows from there.
- A SOA in it's bare essentials can be done for not too much $, but I guarantee that once done, you'll find at least another $2k in upgrades that you'll need.
In terms of lockers, Mace is right, put a locker in the rear before the front. For a time I had a front locker before a rear locker and I blew through birfields like they were made of glass. Not a good idea.
As for springs, running longer springs front and rear is a great idea as it gives you tons of more flex. However, the stock springs work perfectly well. I recommend running the stock springs to begin with and then consider upgrading to longer units at some point down the line.
The best piece of advice that I can think of is was to do one modification at a time with plenty of driving time in-between. I cannot tell you how many times I've changed my mind on various projects and modifications after driving, and wheeling, for a while. Don't rush it, there is always more time to build, and rebuild, your truck.