Wayne at AHR puts a real nice on. I did the CZ #1 Upgrade which included the 3 pos safety, single stage match trigger and straighten and fill bolt. The whole deal cost me $500. You'll need to call Wayne to ask him about just either installing or selling the 3 pos safety.

Here's a link to AHR

http://www.hunting-rifles.com/CZ/CZowners.htm