Yea I dunno about the Gt-40 heads but on mine all i did was use the original fitting, I just hack sawed the tube off close to the fitting, put a pult in and welded it shut, and bolted it back up. Works great and its free
Like everyone said you can buy the plugs from ford. I was helping a friend put a new engine in his 5.0 and since we hadn't thought aheah and bought the plugs we just used a couple of his old spark plugs worked fine. On my car I ahve never taken the tube off of the back of the heads. Where it bends out around the passenger side head I just stick one of those heate rcore bypass caps on it where the hose to the air pump used to go. It was a perfect fit.
Like everyone said you can buy the plugs from ford. I was helping a friend put a new engine in his 5.0 and since we hadn't thought ahead and bought the plugs we just used a couple of his old spark plugs, worked fine. On my car I have never taken the tube off of the back of the heads. Where it bends out around the passenger side head I just stuck one of those heater core bypass caps on it where the hose to the air pump used to go. It was a perfect fit.