Ron the easiest way to explain it is you should be able to take your back wheel off, and be able to wiggle and pull the sprocket out of the wheel without having to remove anything, bolts or otherwise. The sprocket bolts to the carrier, but its meant to float free in the wheel, the only contact is the rubber cushions in the wheel. If your wheels not set up that way then its wrong. And the CZ's are very sweet rims designed to be the lightest they can possibly be and still survive on the street and track. They're are designed to use the least material possible to get the job done. If you drill holes in places where there shouldn't be any you will destroy the structural ridgidity of the wheel, and make it completely untrustworthy to ride on. Plus the drivetrain shock from no cushioning will tear those bolts out quick, since there's no support built in whatsoever to support those custom drilled holes
I forget the members name that you bought the bike from, but he put a lot of work into that bike to make it nice, including one heck of an engine
and I doubt he screwed something up as simple as the rear wheel. You've been running that rear wheel for quite awhile now, I'm sure if there were any crucial bolts missing you would have felt something strange long before now, especially with the power that motors putting out
Rear wheels are pretty simple, either they fit together and work right, or they don't. If anythings missing or wrong you would have known the first time you test rode it. It might be you're not quite able to explain it right...I hope its all good, cause those are spendy wheels to replace
Like somebody else mentioned, the shop has never heard of CZ's (which I find almost impossible to believe ??? ) yet they know exactly how to "drill them" to make them right?
We're all just trying to help educate you and keep you safe.....on a bike you only have 2 wheels, and you need to know everything about them is 100% right