I would suggest if you are looking at doing this to look at insurance costs, I am not sure you will get any insurance and apart from that the cost of speeding fines is cripleing (I know I sold my Evo because of them).
If you are keen and can do most of the work yourself then I would do an SAS.
You need to make front hangers for the leaf springs and bushes,
rear hangers for the shakles,
shakles, a set of bushes,
caster correction wedges to correct the pinion angle,
steel and ball joints to make a crossover steering arm,
Plates to move the power steering box forward on the chassis,
modify the front radiator crossmember (BFH Big Friendly Hammer), extended steering arm (or a spacer)
and a few u bolts,
to match the front you will need to make rear spring hangers,
longer shakles for the back.
Then you need to buy the following bits
Front Axle
I would do a full bearing kit on the new axle,
install a locker into it (or a LSD (breaks less bits)) So you actualy go further
crossover steering arm's (Jaffa's or a factory modified the way a certifier will accept and longer stud's for one knuckle)
Leaf Springs (you can use your rears in front and a few leaves from a junkyard spring)
Grease
Oils to replace those in the diff
Driveshaft (You cannot make this it needs to be certified)
Rear springs from a Falcon or something similar length and spring rate or after market rear springs.
the Gas, Cutting disks, welding wire, drill bits and all the workshop tools.
Certification.
Depending on what your abilities are you will have a truck that is modified but can be driven around by and IFS Surf with a front and rear locker
It depends on how you drive and how much money you want to spend (you will never get it all back) and a SAS is cooler but going further is better. For me I think the best money would be buying one half done or complete like hosehustler
with your 4wd I would look at replaceing the current front diff with a Supra LSD unit, there is info on this site about the swap. After that look at a rear locker. Then look at the brakes and do a rear disk conversion. With any vehicle a solid axle swap does not stop at just a swap. The front solid axle is stronger but there is a lot more that need's done.
Also I would look at finishing one project before you move onto another, that way you can sell one to support the next one and the more you change you mind and put people off now the harder it will be in the future when you need to ask a real question, or a hand to do something. Smaller steps usually work better and the best truck driven by the worst driver will not go any further than a standard truck driven by a good driver.
EDIT: Spelling

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