I'll be using the three existing threaded holes on the cam to attach my adapter to. Here I'm drilling and chamfering for some 3/8" flat head cap screws. This should work pretty good and it won't add much weight either.
 

The next thing I'll be doing is attaching the cam to the base. I had a couple of ideas here but the easiest way was to weld them together. Before I welded anything, I wanted to make sure the two surfaces were nice and square. To do that I took a clean-up cut on the end of the cam so it would be square. I did the cut on my milling machine using the same tooling that I drilled it with.  Here I'm using some 1/4" all-thread that is placed through both pieces to use as a clamp.
 

Here is the bottom along with a few different size washers and finally a 1/4" nut to finish it off with. Once I had everything clamped in place, I used my calipers to make sure the cam and base were centered.
 

The light socket had a really short pull chain on it which I didn't like. And I didn't want to have one of those couplers visible while holding the two chains together so I took the socket apart and added the one I bought.
 

Some sparkplugs have a screw on top so I made sure to buy one like that. The reason for this is so I could attach the pull chain to it somehow. After playing with it for a few minutes, I didn't like how things were going. Time for plan B.
 

I found another screw on piece that I had laying around (bottom) and decided to make a small change. While I was crimping the first one, the material cracked and I wasn't happy with it.
 

The reason it cracked is because the wall thickness was too thick so I sanded my other down to make it thinner (arrow). This should allow me to bend or crimp this area much easier now.