Your still comparing apples to oranges in the first post, and when the motors are in trucks, the torque output kind of makes a large difference. So yeah 50lbs is a lot. And I'd assume that if chevy did make a 5.7l motor it wouldnt really make much more power than the VK. You can easily alter the power output of the VK with some small changes to the variable cam timing. Either way there isnt much of a difference between the truck motor, and Nissan has yet to really make a high performance V8 for road cars so I wouldnt use them in comparison with a motor GM has been using in race cars for over 50 years. Apples to oranges again.

They both have their advantages. But I'd still go Ford 5.0 over either one. Yes its more complicated and taller, but it rev's higher stock, makes tons of power with nothing but ecu tuning and can make all the power of the LSX motors with less displacement and less work (cams, tune exhaust and your almost at 460-480hp with 7500rpm+) and what it lacks in torque it will make up for in broad power that is adjustable across the range and higher revs.