Welcome to the forum.
To answer the first question, yes, there are plenty of XT parts of around the right age, just depends on how perfect you want them.
Is it worth restoring to factory standard? Only if that's what you want. There is a broad cross section here, many like things as they were, many take newer bikes and set them up as older models, just because they like that style, and many (like me) set the bike up the way I want / can afford to.
Whatever you choose to do, there is a wealth of information and knowledge here and the Zaskar is an all time classic, so you have the perfect frame for your retro project.
Enjoy, and don't forget to post pictures... cos we just luuurve them pictures