has anyone removed ef/el engine and gearbox (auto) as one unit, up through the bonnet and then reinstalled it as one unit?

can you do this?
are there any problems to look out for?
is it easier to remove both or break them down and remove one at a time??

removing these is only half the problem as Im wanting to install both gearbox and engine into a second vehicle - ie transfer engine/box from one vehicle into another.

the idea to install engine and box as one unit to avoid the hassle of trying to tighten the bell housing bolts with no room against the firewall - can anyone give me a few hints?

all feedback appreciated