When i rebuilt my sbc, it was pretty easy. I just unbolted crank shaft and pushed out the pistons (after marking every bolt/part so i knew where they went back in). My opinion, i would pull the motor out if you are going that far. You might as well get the block cleaned, honed, check for cracks and do it right. Also, it will probably be easier to put back together on a stand so that you are not trying to do things upside down. Just my thought on the matter since i have never put an engine together while still in a vehicle. Everyone else could tell you better about that.
Chris
