well, that book bajas & buggies, has avery basic modification you can do to a baja in thare. those things have changed little over time.
What HAS changed is all the little doodads, gizmoa, and aftermerket parts choices.
All the cool gidgets in the mags still wont do any good if you cant take it out and beat it without breaking it.
Things Ive learned
1. KISS keep it simple stupid,,,,, the more elaborate the more $ your throwing into it.
2. a type one trans is tough enough for regular off road use as long as you dont get air and let it slam dowm under power. BAD ,, very BAD!!

contrary to what others say, most bajas are running type one trans just fine. (but a bus is stronger)
3. a class 11 chenowth cage is worth the money spent, it already fits and it works great.
4. you can always do more later after you get it running and rolling.
5. the cheaper it is the less your significant other gripes about "that damn money pit haha bug"
6. do your homework when buying parts. there are alot of oprions out there and prices vary alot. I've seen combo link pin spindles for $310 to over $550.
7. advice is cheap and its always available. But good advice is priceless.
8. drive it like you dont want to break it and usually wont break.
9. BUY ONE ALREADY STARTED.
I got my baja, full score legal bumper to bumper cage, fuel cell, cut & turned beam, new centerline wheels, good tires, all custom wired, baja 2 tube bumpers, sheetmetal door panels, alum dash and head switch panel, one peice race front end and rear fenders, 6 fox shocks,,,, all this for,, get this $500 bucks. SCORE DUDE SCORE!!!!!
Ive since replaced the original momo, it had a cracked case,, put thing front end on, 2.5x2.5 arms, and it has over 500 desert pre run miles on it.
IF I were to build this I would have countless hours, and at leads $3000 into it.