wouldn't take that long really - if i was doing it i would set aside 2 days to do it on my own without rushing but i reckon its doable in a day (a long day mind). And by that i mean swapping over all the suspension, brakes, engine and interior (not including the actual dash).
I think on first day i would drop the engines from each car, and swap the suspension and brakes over and remove interior from new car. And then on 2nd day stick engine in and wire and plumb it up. Bleed the brakes and fit the interior.
There are somethings that it would be sensible to change for new stuff during this though, it would be silly to not do a full service at this point and changes belts etc along with a load of suspension bushes, new discs, drums, shoes and pads, and new clutch kit etc.
And remember that not all this stuff will necessarily need swapping, the interior maybe ok in the donor car for example.
This kinda thing is not a hard thing to do at the end of the day its just finding the time, alot of people can't just take a few days off work to mess with a car but i work from home most of the time, family owned business so i can take a few days off not problem if i need to - and i also have a spare car to use if i need as well. Without that such things become way more of a hassle