That is really easy to do. We do that here all the time, however I hop you have a lift. To pull the engine and tranny together with the headers attached, pull it out from the bottom. disconnect everything as usual, and undo the 8 or so bolts that hold the k-member in and viola, engine on the ground. You will have to disconnect the shocks, which means you have to pull out the springs, but no big deal....usually.
it can be done in 20 minutes if you have done it several times. Otherwise, look for it to take you about half a day to make sure that everything is disconnected and so on. Hope I have helped you out. Feel free to call me with any questions you might have.