Good recommendation to read the books / read the threads (I'm particularly partial to this one; I was where you are now:
http://forums.pelicanparts.com/porsche-911-technical-forum/789817-start-maintenance-end-disaster-opportunity.html) and figure out how comfortable you are with what you'll have to learn (with the help of the board, of course!)
An important question: What Pelicans / PCA members are near you who can drop by? It really helped my confidence to know there were other experienced people who could put their hands on my parts and tell me what to do when I was stuck.
I would split the case. My car had ~ 60,000 miles on it and the intermediate shaft bearing was showing some wear as was one other.
Budget: I think $7-10k is reasonable for doing it yourself, but wildly optimistic for including an EFI/ITB conversion.