Replacing engine without removing the tranny?

I just did what you are planning to do. Removed 318 and installed 340.
Remove hood(two people is a must), radiator, fan, battery, exhaust manifolds, engine to trans brackets, starter, trans dust shield, flexplate to torque converter bolts, motor mount bolts,engine block to trans housing bolts(5 of them), and place a floor jack under the trans to support it. Its best to have two people. Pretty straight forward. Take care with the wire bulkhead on the firewall. Lift a little and tug forward. The engine will seperate from the trans. Make sure that you have plenty of room above the engine lift. Use a short chain.