kmw1970,
Mike Stannard dba Tornado Technologies is the KING of all things threaded:
http://www.tornado-technologies.com/services.html
Tell him that I sent you.
Mark McWillis dba TROS/ TheRiddleOfSteel also does a sweet conversion:
http://www.trosusa.com/
Actually, when I purchased my KADET, it was a "turnkey" item: complete KADET pistol (not just a conversion upper & mags) + threaded adapter installed, thread protector & 2 magazines from Tactical Innovations. CZ prices have been rising so quickly, that T.I. dropped that package offering as the profit margin was getting pretty tight. They used a TROS adapter with a fairly wide shoulder. It sold for $600.
One thing that I would suggest doing is to obtain an HKS 9mm magazine loader & mill down the loading finger to fit the narrow accessway. An upLULA loader works well too with that mod.
These are fantastic platforms for suppressor use; accurate, reliable, full-size & weight, unobscured sights & HOLLYWEIRD QUIET with an SWR Spectre suppressor & LAPUA Master-L ammo.