Welcome Hdbjsafari,
Owning a large pile of CZ rifles in various calibers, I can say I have at least some experience with them.
All have been very reliable and very accurate except one.
Strangely enough, it is the only one from their Custom Shop that I have ever had.
It is a .500 Jeffery caliber.
Ordered it brand new and it will not allow me to quite shut the bolt on A-Zoom brand snap caps.
CZ's Gunsmith tells me I need to try Superior Brand live factory ammo, before I throw myself down on the floor, screaming and kicking.
I shall try his suggestion but with Kynoch brand, (factory live .500 Jeffery cartridges, of any brand are not so easy to come by where I live).
Regarding modifications:
I like 24" barrels (I'm about 6' tall) and have that on most of my rifles, no matter what brand they are, including the .500 Jeffery.
But I unashamedly admit, some of my rifles are 23" barreled.
One is 22" and one is 20".
The 20 incher is of all things a 6.5 Swede, Mannlicher style stock (also a CZ).
Come to think of it, I have a .22 LR of about the same dimensions (CZ) so, that makes 2 with 20" barrels.
However, 24" is about right for me in most hunting conditions I have enjoyed over my many long years.
I've never hunted in a tropical jungle but, I have spent more time in this jungle or that, than most Americanos have.
For jungle big game hunting, I would go for 22".
That's not Gospel, it's just what I like for my use.
Also, I like to have the bolt handles cut off all my CZ 550s and a new one WELDED on to more or less match the old "Pre-War Orberndorf Model 98 sporting rifles".
Refer to Jon Speed's excellent book on those incredible rifles (the best hunting rifle the world has ever seen / my opinion again).
Or, look at an original Surplus 6.5 Swede carbine handle.
Those are nearly the same, nearly.
The same as one person mentioned here, I like a large white bead front sight, as my eyes are aging.
I have not widened the rear sight on any of mine but it sounds like a good idea if I ever start having trouble with the rear sight some day.
The safety and striker shroud is clever and extremely functional on the CZ 550 however, I have mine removed and the Model-70 Winchester type installed, primarily because I am OCD and I like the striker to be blocked, not just the trigger, plus I think it just looks a little classier.
My .458 Lott has an after-market single stage trigger installed but, I do not like it any better than the factory trigger, perhaps not as much.
Unset, the factory trigger feels a little like a military one to me and I happen to like such things.
I never push forward to set mine, I just use them as they are.
On all mine, except smaller calibers, I have a barrel band type sling swivel installed and the hand raking one in the forearm of the stock removed.
I have all my large bore rifles, CZ or otherwise, reinforced (cross pinned/glass bedded and most have had an extra recoil lug added under the barrel, part way up the forearm, and the recess for it cross pinned and bedded as well).
Splitting one's stock in the bush is not cool at all.
Whatever you do, practice, practice, practice and then practice some more.
If something is going to break, have it be on the range well in time to get it fixed before your safari.
Forget about the bench after getting the rifle zeroed and stick with field positions, especially from sticks.
I recommend using two legged ones.
If your PH uses 3 legged ones, it will be easy to use them if accustomed to the two legged kind but not the other way around.
Help, I'm typing and I can't stop.
Cheers,
Velo Dog