Looks like a good rig. I've never seen the rear shocks mounted that way, we've done a few of these and we always mounted them on the rear housing. This way might make it more stable.
Most of the people that run coil around here just run off road. They find it way to soft for the road but there are systems that can run on-road.
Take it out for a drive and make the old owner take you for a drive. He will be used to the way it drives and will tend to drive faster than someone who has no time in the rig. His extra speed will show you if it's stable or not drivable.
One guy around here bought a "offroad" only coil system and installed it. You can almost push the zuke over because it's so soft. We've named it the drunk horse. It's not safe on the road but that's because he's cut and re-welded it a million times over.