I've just changed the engine in my '3i. I took the rollbar off, split the shafts (which is very easy on these) and dropped the engine to the floor with my crane. Then I used the crane to lift the car up by the front crossmember and secured it with axle stands (I have a set of 1000mm stands). Then I dragged the old engine from underneath, put the new one on the floor and dropped the car down over it. Finally just lift the new engine in to place.

Lee