sinfulrides, if the shock has the coil on it, yes, it will cause the rear of the truck to sit a little higher. Also, keep in mind that because you are adding those shocks, you are also effectively raising the spring rate in the rear of the truck. What you are going to experience is more bumps from the rear of the truck as it will not be flexing as much (takes more force to move the suspension the same distance). This may be good, this may be bad. But, I can liken it to driving around in an F-350 unloaded.
The other thing that you will need to consider is since the shock is taking some amount of load, you are stressing the shock supports more as they are now carrying part of the weight of the truck. The stock mounts should be fine for some amount of load. But, it can also lead to failure of those mounts too. I would need to take another look at the factory mounts.