Yes, I'm sure I saw extended Slide releases were available, I think both CZ-USA but more like the folks at CZCustom have them. Or they should be able to tell you where to get them. Extended Slide releases' are about the most asked about mod on most if not all makes and models of pistols world wide. Frankly, I personally think it's the reason that so many people refuse to go to pistols if they started out using wheel guns. That and the Safetyrelease, or at the very least the Safety Release not being Ambi. And now that you have brough it up and I have said that, I'm going to try to find out out much it is going to take to do that from my collection of CZ's, or as many of them as I can meaning if they even have extended Slide Releases' available. Really do not think they make them for my Tok or Mak. I am sorry I came to this post late, Just a lot going on and even though neither CZ-USA or CZCustom are open at this time of the morning for me, I looked at my Pistols I do have it it seems to me that if anyone will fit your 75B then it's most likely to be the one for the SP-01, But I would still suggest you double check with CZ to make sure. I may well be incorrect about the Extended Slide Release being swappable.
To answer your question about the ambi safety, it's available for some CZ and comes standard on some of the Models also. And yes you can get an Ambi Safety for the 75B no worries.
