First, I'm going to come to the defense of those darned Phillips head screws. They do serve a purpose. When I studied to be an auto mechanic (actually got an Associates Degree in Applied Auto Technology) they taught us when and how the Phillips head screws first became popular. It was in the auto industry. Among their advantages, a Phillips head screw will better retain the driver, so there is less chance of slippage and damage to the adjacent material. It also is easier to align the driver with the screw, and the shaft of the driver can be narrower and more easily fit within the recess wherein the Phillips head screw is placed. These are significant. The solution, in my opinion, is not to replace a poorly made Phillips head screw with a slotted or Allen head screw; but to replace it with a better made Phillips head screw, of proper dimensions. That's a tall order. The choices appear to be: buy some more of the OEM Phillips head screws and replace at the slightest appearance of wear; re-tap with a more commonly available and more robust thread and screw (such as for the M1911); and, among other things, buy slotted screws (e.g., Hogue). Each has advantages and disadvantages.
In theory, the grip screws for the CZ 83 and the CZ 75 are the same. You may find various places that advertise replacement screws for the CZ 75. Oddly, however, though the OEM Phillips head grip screws from my CZ 75 BD fit my CZ 83 with relative ease, some of the aftermarket screws for the CZ 75 BD (e.g., Hogue slotted) fit my CZ 75BD easily, but were not quite as easy a fit in the CZ 83. I figure that there was a greater tolerance in the frame of the CZ 75 BD than in the CZ 83 or perhaps the threads within the frame of the CZ 83 were intentionally treated to make it more difficult for the grip screws to back out during use. HOWEVER, a big negative of the slotted screws is that, to avoid damage to slots, you need to use a driver that is 3/16" or thereabouts; but when you do so, you run the risk of reaming the grip material in the recess wherein the screw is inserted. Hence, the Phillips head screws and narrower driver. So be careful if you do go with slotted screws rather than Phillips.
Anyway, I purchased slotted screws from both Midway (Hogue-advertised for CZ 75) and from Grips4U (advertised for CZ 83). Both vendors were polite, courteous and genuinely interested in customer satisfaction. However, in the case of Grips4U, I ended up not using their screws. Pitch-wise, they were as good as the Hogue slotted screws that were advertised only for the CZ 75. However, the slots were another story. They were too thin to accommodate the thickness of any of my six 3/16" slotted screwdrivers or any of my metric equivalents. The choice was either to use a 1/8" slotted screwdriver to avoid reaming the grip recess, but risk damage to the screw head or to file down one of my 3/16" screwdrivers until it fit within the slot, but risk reaming the grip recess. What to do? I ended up appropriating OEM Phillips head grip screws from my CZ 75BD for use in my CZ 83; I then used the Hogue slotted screws in my CZ 75BD. So, if I were to offer advice, I would suggest you just get a few extra OEM grip screws for the CZ 83 (or OEM for the 75), and make sure that you remove each time with a proper fitting Phillips head screwdriver (In standard size, a No. 2 seems to fit better than a No. 1).
The last couple of points to note: There are somewhat difficult to see rubber bushings ("O" rings) within the OEM plastic grips through which the grip screws go. Take care not to lose, damage, etc. As near as I can figure, they are needed for the OEM plastic grips, but perhaps not for some aftermarket grips. If you're going to order some extra OEM screws, maybe you should pick up some of the bushings. Some folks find that the OEM grip screws tend to back out, and recommend using Loctite or similar. I am in the opposite camp. I am almost inclined to believe that part of the difficulty in removing the OEM screws from the CZ 83 is due to the fact that either they already have some thread compound on them or in the frame's threads, or may be intentionally deformed to make it difficult to come lose during firing. What I did was to take a brass brush and gently "clean" the threads of the screws to make it easier to install and remove. I likewise thoroughly cleaned the frame's threads and lubed with oil. I would rather have a screw come loose than damage the frame threads or have to use a bit to drill through a stripped screw.
I am not an expert in such things, of course, but only wanted to share my thoughts.