Since this comes up every now and then I thought I would post these links which contain very detailed step by step instructions on how to drop the motor out the bottom. While it is very involved, it's something almost anyone can do in their own garage.
I used these directions myself when I rebuilt the engine in my '96 Z28 a couple of years ago.
The first link contains the pictures, second link is instructions.
http://home.comcast.net/~saccani/Jef...l_Pictures.doc
http://home.comcast.net/~saccani/Jef...ne_Removal.doc
Engine Removal
