UPDATE:
I pretty much did the same thing as shown on that website, however, do to my & my shop's inability to weld aluminum, I used a bead of JB Weld before placing the new plug in, and around the top seam. It should definatly not leak now.
I know it looks ugly now, but a little sanding a a touch of VHT will cure that. And yes, I cleaned and smoothed out the plug seat before reinstalling the new plugs.
