While I do agree with Sastra that some behaviours need separating (bedtime and eating behaviours are the most common) I think it is also possible to target bad behaviour in general.
It very much depends on where the bad behaviour comes from but often the difficulty in dealing with it comes from the fact the child isnt used to be 'dealt with'. This when bad behaviour begins to spiral and as you say become out of control. If he is as uncontrollable as you describe then you need to see him as a blank slate - he must currently simply learn the forbidden and not forbidden, when he has grasped this you can focus on the why.
Before you tackle where behaviours come from you need a system in place to control him when he disobeys. This way it is a blanket that covers hitting, shouting, swearing, running off, being mean etc etc. This is the beauty of 'naugty step' - it doesnt matter what the behaviour, they are told once and if they dont comply there is a consequence. (I'm not saying you should use this btw, I actually think at 8 with 'uncontrollable' behaviour he is past naughty step)
For this to work you have to be really committed. The reason many people find charts and punishment systems dont work is because, in all honesty, they dont use them every time. Sometimes they let things go, sometimes they do the punishment but not all the way. Behaviour is a learning process. You have to come down hard now, you can ease off later when he learns to manage his own behaviour. Children need guidance in their behaviour. Sometimes 'because I said so' is the only reason that will do.