So this evening I tried again to level the engine mount, the closest I could get was around 10 degrees off horizontal. And the engine mount was awkwardly assembled to get that; it really worked best as I showed it in the prior pictures, which was around 20 degrees off horizontal.
I wondered if there would be long-term oiling and/or carb issues being 20 degrees off horizontal. That, coupled with some encouragement from AGK in the "4 Stroke Mount" thread elsewhere led me to bite the bullet, admit that I made a poor decision buying that LuckyEarlyBird 4 stroke engine mount off ebay, and buy a better motor mount.
So I bought the "Black V-Frame Mounting Plate Kit" from bicycle-engines.com
http://www.bicycle-engines.com/Black-V-Frame-Mounting-Plate-Kit.html
I had been wanting this mount from the moment I saw it, which was about a nanosecond after I hit "Buy it Now" on the luckyearlybird ebay link...
The frame mounts on this one look to be alot better. I believe this is the Grubee 4 stroke mount.
One thing I really don't like about this cheaper 4 stroke mount (the LuckyEarlyBird one) is that the frame clamps are spaced so far apart, tightening the fasteners simply cause the clamp bracket to bend. Looking at the Grubee mount, it appears that the clamps will wrap around the tubes.
Again, on the cheaper mount, you can't really dial in the angle on the mount, it's relatively fixed, unless you don't want the horizontal plate sitting squarely on the frame clamps. The Grubee mount appears to offer slightly more adjust-ability.
We will see....
Dan, I think this new mount may solve the spark plug interference issue, but I'll still change the plug and boot out anyway.