[DanEC]

I would say you have at least a couple of options depending on what equipment you have and feel the most comfortable with. Being as your engine bay and transmission tunnel are so wide open I think you could drop it in from the top very easily or rig up a frame to mount the assembled drive train on and slide it under and lower the body down around it.

With a good hoist and a crank tilter on it you should be able to drop the engine/trans in hanging from a steep angle from the side, slowly level the assembly out as it's lowered and have to do very little jigging of the hoist side to side to get the engine in it's mounts. The front tire will probably need to come off to allow the hoist leg to slide under the car. At some point, unless using a second set of hands, you would need to prop the tail of the transmission on a 4-caster furniture dolly or something to hold it off the floor and let it roll back as the unit is lowered and leveled out. Once the engine is in it's mounts, the tail of the transmission can be jacked up to get the crossmember mount under it and get the bolts through the engine mounts.

Good luck.