Has anyone done that conversion before?? If so what are the costs and issues I would encounter?? 

That is highly unlikely as the cost is or will be astronomical. Sourcing second hand TB48 driveline is also not that common.

Apart from the body there are differences especially electrical system, you would need the tranny as well as brakes and even handbrake is different. Getting the engine and transmission assembly, electrical looms etc from a donor rolled over vehicle perhaps.

Going LS V8 or Ford Barra straigth six is easier due to much greater availability of donor parts.

Regards