Good advice above. If you're not inclined to build one yourself I'd at least invest the time to learn which parts are best and best for you. Pay particular attention to barrel profiles as many people buy the wrong barrel then regret it once they figure it all out.
If you work with your friend that's fine but you make the choices on the parts, not him. That means lots of research. I wouldn't want anyone making those choices for me. If you don't know what you want how can someone else?