Im a first class metal worker second class welder, trust me, its a HUGE job, you will need to modify both the doner and parent materials, the inner guards are not that big of a issue i.e.( (same as tubbing) (still a huge job in itself though)) its the exterior panels mating up on all axis and curves that will be the problem.
It would be a pity to do it when in the end it may turn out like a dogs breakfast.
Dont get me wrong, if you can do it go for it, other wise just be aware that it will take a top quality fabricator ages to do it, and ages will cost alot.