I know this thread is a bit old but for those that trun into it regarding the pos cable on the firewall and routing over the valvecover, just disconnect it from the firewall by removing the large nut and push it under the intake while pulling on the other end of the cable where it comes from under the manifold near the valve cover and you will be able to put enough slack in it to pull it completely out of the way of the valve cover, just pull it towards the radiator.