Billybooo.. not everyone is like you. Some people are more ambitious than others. Alec is an extremely smart kid.. he knows what he'* talking about.
Lakeville: The transmission break down is also in the Factory Service Manual [FSM]. I'm pretty sure it'* the same as in that book you recommended. I've seen both, but only own an FSM. I don't see a difference.
The biggest problem you will run into, is removing the engine/trans. That scares me more than taking apart the tranny.. but that'* beacuse i'm only one guy, and a young, weak 15 year old at that. The 2nd biggest problem is having a large enough, sterilized area to actually disassembly everything in. It is extremely important everything be kept SPOTLESS. You don't want a piece of dirt ruining your hard work, now do you? Third biggest problem is getting QUALITY parts. Not sure where you'd go about getting them. JCWhitney has the rebuild kit for the TH-440-T4 [87-91 Transmission], but i'm not sure if I'd want that going into my transmission [no clue about it'* quality]. So just be aware of that too.
IMO, if you have all the necessary information [break downs, dis/assembly procedures], and are mechanically capable [probably a good way to proove this is if you aren't daunted by the pic Dr. Jay posed].
Also, the reason why Transmission shops have a low success rate on rebuilding FWD transmissions, is probably because they have HS dropouts working there. Or because their documentation is poor [like a Haynes Transmission rebuilding manual
]. Plus owning the car makes you more cautious, especially if you have the love and determination for that car to rebuild a FWD auto trans.