First top end rebuild attempt ever...couple questions

[shiner2001]

Alright, after one ride on my "new" 2001 DR Z-250, I noticed a few drops of oil dripping from the bike and quickly packed it up and took it home. I originally thought it may be coming from the gasket on the starter motor cover (as it was obviously unseated), but after a little more inspection, it is pretty obvious that I am leaking from the head gasket. Since I'm going to be breaking into the engine and the bike is of somewhat unknown past maintenance, I'm going to rebuild the top end while it's apart (wouldn't surprise me at all if it has never been done). So, that being said, I'm curious what all needs to be done for a complete top end rebuild. From all that I have read, it looks like a new piston and new rings are in order, as well as the obvious such as gaskets. Other than that, what all do I need to replace/check? Also, is everything available in a kit, and if so, what are some recommendations? I have a service manual and am not worried (too much) about screwing anything up (more worried about replacing the fork seals, may have a shop do that one for me). I've done quite a bit of looking around and found several good threads about specific parts of a top end rebuild, but am kind of looking for some general advice, as well as anything specific to this bike, which is not as common as many others.

So, there we go. Soon to dive into my first bike engine ever. Hope the Jeep doesn't get jealous.