Before you go drilling the frame and ordering parts for a different gun from CZ-USA, let me save you a LOT of time.
I asked the same question a few weeks back and was steered in the same wrong direction you're headed. Luckily a member (thank you marcodelat) gave me a
link to another board.
A man named Norm Sutton in Lakeland, FL makes/sells the part you need. He's awesome and he saved me from drilling the frame of my 1986 CZ 82. If you send him $5 via PayPal, he'll have them in the mail in no time.
What kind of trigger guard latch do you have is it solid with on end thinner than the other and a groove in the thick end for the slide stop spring to rest in OR is it a tension pin, which looks like a tube split end to end with a thinner pin inside?