John,
Just have whoever makes the leveling spacers leave the tapped holes out. After you mount the spacers (that's using the counter-bored holes) align the new mounting base to your liking, spot the holes for position and drill and tap the spacers accordingly.
All,
If any of you are unable to find someone to make spacers just post a response and we'll come up with a way to fix you up. I'm an engineer and have a small machine shop that I horse around designing and making my own stuff (mostly in the winter when the riding isn't as good), but don't really have the time to make any of it for selling and that just isn't my goal - I just enjoy riding & motorcycles. Anyway, with that said, if I can help somebody out, I'll do what I can. I also have a lot of professional contacts that make a living from machining and fabrication so I suppose I could have it quoted and see what the cost is after I know how many are interested.
Todd,
Not sure if you're seeing this or not, but would this be something you could add to your product offerings?
Ride safe,
Jeff