Guy that was going to build my 6.0 before I sold it told me this...."The 6.0 is really alot better. I put in a 5.3 with headers, cam, rods, springs, heads, LT's and ory on a truck. I also dropped in a completly stock 6.0 on another. The trucks actually raced and the 6.0 blew it away" IMHO dropping all this money that you are wanting to in the 4.8 would be pointless. You can honestly probably find a block for what your spending on a few mods that you would do to the 4.8. It would be alot more practical to find the 6.0 and go ahead and put heads, cam, rods, springs and other things in that you would do to the 4.8. The parts for the 4.8 would be the same for the 6.0 as they are both ls based motors so why not just find you a starting platform 6.0 for around $200-$500 depending on what parts are already in it (I would much rather go with something completly bare so you can upgrade parts if you want to go fast) and add the parts to that instead the 4.8?