The other posters have covered things pretty well, and I would just add a few comments.
The original 21H/22F butterknife bolt handle does stick up a bit when opened, and requires a higher scope mounting for the bolt handle to clear. If you are used to the old FN Mauser scope safety on the left side the 21H/22F safety works exactly the same way, except that as Kutenay has pointed out, it does not lock the bolt as the FN Mauser safety did. The original bolt sleeve safety works well with the higher scope mounting IMO, however if you want a lower scope mounting the bolt handle has to be modified, and in that case the original safety is difficult to disengage because it lies right up against the ocular bell of the scope. So a low scope mount requires the 21H/22F bolt handle to be modified and also the safety replaced for best results. If you are used to the Win 70 type safety then the equivalent design for a Mauser 98 will work perfectly.
The 21H/22F do have two cost-cutting measures that I am aware of compared to a standard 98 Mauser design: 1) the magazine box is stamped rather than milled integral with the trigger guard and 2) the magazine follower is stamped.
The ZG-47, OTOH, does not need any bolt handle modification for a low mount safety. It also has a stamped magazine box but at least on my sample, the magazine follower is milled. FWIW, the late Jack O'Connor wrote in the Rifle book, "In my opinion the best Mauser-type action ever made in Europe was the [ZG-47] model turned out at Brno in Czechoslovakia." although he called it the ZKK, which was a later model. However from his description, plus a picture of the custom .280 Rem that he had built on an action, it clearly was a ZG-47. Also, a year or so ago the Champlin Arms website had a ZG-47 for sale with the following, "The great metalsmith, Mr. Tom Burgess, told me personally he thought it was the best action made in the post-war era."
Also, unlike FN after about 1948, Brno did not cheapen the action by milling out the internal receiver ring on the left side - they are all "C" ring actions.
The double square bridge scope dovetails have been unchanged from the 21H through the ZG-47, ZKK600's and CZ550 series, and have a recess in the rear bridge on the left side that acts as a recoil shoulder. Brno/CZ rings have an extension on the rear ring that fits in the recess. As for rings, I believe the Talley's only come in one height, Warne makes rings in two heights and Alaska Arms come in three heights. I think the CZ rings come in one height. Lynx and Burris also make rings. Most of these rings mount the scope anywhere from around 0.3" to 0.5:" above the top of the dovetails. If you want to retain the original 21H bolt handle, the heights of these rings are somewhat on the low side for most oculars, with the exception of an old set of Lynx high rings I have which are about 0.6" high,but original Brno mounts show up from time to time on eBay that mount the scope even higher, up to around 0.74" above the dovetails. The original Brno mount bases are quite intricately machined and despite their blocky, massive looking bases are quite light because they use aluminum rings and bases with a steel clamping jaw and screw. The clamping jaw is a T-shape with the sides and top of the "T" supported on all sides by the surrounding base, and the bottom of the "T" on the rear base fitting into the recess in the receiver ring.
