I am doing a build with a 5.3 (6.0 would be great, but $$$). I think you will be happy either way. The 5.3 that your friend has probably lost alot by going carb., and big cam. All of the people I have talked to say the 5.3 works great and even better with some ecm tuning.
Keep us posted with what you decide.
Hay, look at me... I have a signature.....