For the most part your truck is bone stock and everything bolts up and lines up. Swapping in that monster V6 will change EVERYTHING as nothing stock will work from the bell housing forward and EVERYTHING will be hard to find or need to be custom made/fabricated. In the end the WOW factor won't be any greater than the 409 that's in it now. 99% of the car show people don't even know or care what a 478 is, it will just be another big truck with a big nondescript motor...
Get the 409 running and see how your buddies react to it...I bet they'll love it!
My .02 cents,
Mike B
