Keeping the donor running and driving is one of the "magic" things with this build
Apart from the obvious things like the bonnet doors etc., the only "technical" thing the builder needs to do is disconnect the front and rear lights, even the fuel tank can be moved with-out disturbing the pipes.
If every thing goes right it should be possible to drive the donor into the your garage at 8 am on a Saturday morning and drive out an Alpha at 4pm Sunday afternoon.
I feel a time lapse video coming on