first off, buy a rule book from score. that will anwser your question about turbos and such. they are illeagal.And they will NOT allow you to run in score.
2nd, there is no such thing as bullet proff in baja.Dont belive me, ask the local police cheifs (ok bad pun). but even the million dollar trophy truck's brake.
3rd, I would recomend running a 4wd truck in the 1000,silt bed's, water crossing and hill climbs get torn up before the 7s,7sx trucks come threw.And it will pay for its self.hell the silt beds are just flat out nasty.
7s, and 7sx are both limted to 12 iches of travel in front.stock track width, plus or minius 2inchs.
stock mounting location's must remain, you can add material to them,but you can not move the position.
(ie no extend raduis arms)
boils down to, something like autofabs econo kit is the basics of what you are allowed for a ranger.both 2wd and 4wd.and you can run beefier coil buckets if you like.and you can do things like the stock stubbys radius arms on heims, and the piviot end's on the beams with heims or uniballs.you can also plate them in and such.
stock type sterring, no rams, or crossover etc. stock sterring box. you can run a sterring quickner...ranger boxes are kinda slow.. and after market pumps are ok.you can beef up the sterring linkage,runs heims etc,but must remain stock config.
spicer blue booted, tierod ends and ball joints seem to do allright.
rear spring lenth,can be as long as any man. mini truck, that is in production that runs in the class, ie ranger 55 inches, toyota 57.5. a ranger can have rear leafs as long as the toyota. etc.but they must be mounted as they came on the truck, for a ranger that would be on the frame sides.not under the frame like a toy comes.you can flip the shaclkes.and beef them up and the mounts.
shock's and shock mounts are open as long as the front shock mounts dont protrude threw the hood.
rear end most everyone runs a 9inch, but it must be + or - 2inches in track from stock. 31 spline minium with good guts, 35 spline would be a better choice and 40 would make it dam near bullet proof.Id also run a spool
full truss would be a wise thing.
gears your going to want in the 5 range.for 33's. thats the only draw back about 4wd, is your limited to 5.13's. I dont recomend 35's on the ranger spindals.
you can also box/plate the frame.
eng must be mounted, + - 1inch from stock location.
cab must be mounted in stock location.fire wall must remain in the stock loacation as well.you can get away with massaging it a little for tire clearance.but must have a stock apperance.
trans, is open as long as it is the same man. as the truck...ie you can run a c-4,c-6,t-5 etc. but you cant run a th350,400 or 727 etc.
If you run a auto,your going to need a few good coolers to make it last.and some good guts inside.
M5 would proably do the job if you were good to it, and was in great shape at the start line....
fuel cell is a must, same with 5 points,and some good seats.mastercrafts,beards etc....your back and ass will thank you the better of a seat you get.
full cage of course, for this you will dam sure want a rule book and talk to savage before you start to build it.