I have a 21F and a 21H. The full stock one is an 8x60 with round receiver. It does have a cutout for the bolt-guide, but the bolt does not have the guide. The bolt on the later 7x57 21H with scope rails does. The bolt handles were never modified at factory to clear low mounted scopes, I believe, and all I have seen so far were modified by a gunsmith. The only exception would be the ZG47 style bolts, that may have been fitted at factory during crossover years.
The reason the model numbers are confusing is because in Czechia, the guns are only known as Zs (to denote Zbrojovka Brno early models as opposed to later name CZ, Ceska/Ceskoslovenska Zbrojovka Brno). Z designation could have also been a naming carry over (they started with Zetor - Z-tractor and Z designation for their cars), so this could have been Z-rifle and people took to naming it Zetka (zet) as nobody used Zet but rather Zetor for the tractor. In all cases I'm sure Z stood for Zbrojovka. And then they were distinguished as rifle or carbine and full stock or half-stock. No model numbers as far as I know. I keep wanting to visit the factory and ask directly just for this, as nobody seems to know the model numbers.
I love these Brnos the most, but I do not like that the safety does not lock the bolt in closed position when on. I love my Brnos/CZs but there always seems to be just that one thing that makes me cringe. I think mod 21/22 with the ZG 47 bolt is probably the best combo ever. Small receiver, nice stock, nice bolt, smooth safety.