Depends on what you want. From my understanding the rule of thumb for an off road suspension setup is around +6 degrees of caster, this seems to be the ideal amount to work with. However, that number can change depending upon the application and vehicle.....and by that I mean that some kits may not allow for that much caster. In addition, every car is different so you may not need/want that much. So in that instance you should just work with your stock measurements to retain the drivability of the vehicle.
As far as adjustment goes....I don't see any way to shim or adjust the a-arms. So before you weld everything up I would tack weld everything and get some proper measurements utilizing a 3 point caster swing with wheel bubble levels at ride height. These can also check your camber......they are around $100 and work as well as a laser alignment.
https://www.google.com/shopping/pro....3&ei=U78dVMTeAubjsAT5moC4CA&ved=0CIEBEKYrMAI
Caster is determined by the angle of the upper and lower balljoints from 0 degrees, unless you can establish true 0 from your lower balljoint and then measure perfectly to center pivot on your upper balljoint with an angle finder you will never get an accurate measurement. When you perform a caster swing from center you are establishing your true baseline geometry while measuring the change from center. After you have those measurement you can calculate your caster using a simple equation. This is what you do with the bubble levels, and it is just as good as laser alignment when done properly. A laser alignment just does all the math and calculation for you to speed the process up.
You need to get some REAL baseline numbers before you adjust anything, right now there is no way of knowing where you are at based on what I saw in this thread.
