Erm, it doesn't take "serious work."
Actually, all it takes is a 5.0 T5 pilot bearing, I BELIEVE you can even keep the 2.3L clutch. However, the crank has to be machined for the pilot bearing, or you can buy a bronze bushing that fits the hole.
5.0 T5's have a larger diameter and very slightly longer input shaft. 4 cyl T5's have a much lower First gear and a different bearing to accommodate it, and different gear ratios, but they are otherwise identical to 5.0 T5's.