[Xeen]

Conventional wisdom might suggest that it isn't a good idea to hard plumb your fuel lines but it all depends on his setup, if he is using poly motor mounts they aren't going to flex as much as rubber, also if he leaves enough length for the line to absorb any flex to where it doesn't actually put any significant stress on the line between mounting points it will be fine.
I don't think he is going to be racing the truck anyway those days are over, since he isn't going to be stabbing the gas I doubt that engine will ever see over 3500 RPMs so it isn't going to be moving much.
If he was going to be beating on it I would agree with you guys.