Reading this makes me wonder what you're wanting to a chief in the end ?
Many big engines have been fitted to 90's & 110's with different result.. Fitting a V8 is possible - has been done many times, even bij te factory - and the auto box also is possible but you run into all kind of problems. Depending on where you are located you could end up with all kind of legal problems, too..
So have all the fun you want and cut away but remember that making it go is only part of the project : safe handling and stopping are way more important.. The were never build for speed or to pass the Elk test...
Have Fun !