6 to 8 conversion

You'd want to get a donor car. You want the entire front end. There shouldn't be much you need outside that, beyond some small misc items.

Figure 8-16 hours labor at a good mechanic. Pricey.
 
To do the conversion from the v6 to the 5.0L there are going to be some major alterations needed. Like the previous note the best way to go is to purchase a donor car. Now if your not completely set on dropping the 5.0L in their you might want to consider a 4.6. The 4.6 bolts up the same as the 3.8 and there are fewer alterations needed. Either way they will both take time and it might take a few weekends. Checkout www.stangparts.com they have some decent prices on used engines and you might be able to get a good deal on parts.
 
Yeah i considered to swap my V-6 with a 302 but discovered that swapping with a 4.6L would be a little easier with my 1999 Mustang. Even though a 3.8L is pretty much a 5.0L minus 2 cylinders. Its a costly and timely project. So far i have the old motor out and getting a dressed, long block saleen motor in a couple weeks. -william arthur