Hi -- for my first longest Kenya Trip I went with the largest operator in Kenya -
http://www.sunworld-safari.com/ - while it was organised by the guide based on SA who I met up with Amboselli this turned out to be a great choice.
Recently I go direct with the owners of the Entim Camp, in the Mara, who also have facilities/camps across the country. Flying is far far better for me than driving between camps, but that is how I went first time. But you have your arrangements in place. Enjoy the roads "hee hee" and the "interesting" driving conditions.
I strongly suggest you have your company take you to David Sheldrick's in Nairobi (in the National Park) -- see my other post for details.
If you look at my
Flickr Albums for 2016 - you will see I went to Samburu, Nakuru, Bogoria (which was a little disappointing and only good for Pelicans and Flamingos - the lodge was also very run down), The Masai Mara, Amboseli and then on over to Tanzania where we went down to Ndutu, via the Crater and Serengeti and ended up back at Kilimanjaro. Since then I have spent the majority of my safari time in Kenya in the Mara.
I travel on Safari quite a lot of gear. BUT this time I will be carrying 2+ bodies and 4 lenses with me - 600/4TC, 400/2.8TC, 100-400 and 24-120. AND 2 Z9. Most of this will come with me into the cabin, certainly the 2 bodies and 2 large lenses.
I may take a 3rd body but currently am debating this(see below).
I will not be taking a regular tripod or monopod but have a not-a-tripod-support that allows me to shoot astro off of a table If I wish to. I am normally asleep by 8pm.
I take an empty bean bag, panning plate, external field audio recorder and mic's and an arm that helps make panning video shots easier. 30+TB of external storage, 2 spare ENEL-18d batteries and a power bank PLus 16"MBP and lost of ways to charge/extension cables etc. I use an iPad for quick looks in the field using Snapbridge.
Normally Job 1 after each game drive is to offload images (while I shower) and make an immediate backup while we eat. Then run through images to find good ones for the daily report. etc.
In your case I would STRONGLY recommend taking 2 bodies that work in the same system. For me 2 Z9 was the right answer. ONE Z9 and a Z7ii or Z6ii might do the same job for you. I suggest using CF-Express Type B cards in all bodies. This makes offloading images much quicker/easier.
Taking a Fuji limits what glass can be used on each body.
The 600 and TC14 are my go to lens for over 65% of all the shots I have taken on Safari in Africa. EVERYTHING looks better given the field of view of a 600mm provided that there are not excessive heat effects AND a 600mm allows you to NOT disturb your subject so you can capture more natural behavior. You simply will not achieve great shots of, for example, a cheetah chase with anything shorter. Lions and Leopards up trees, Crocs, Hippos, & Elephants fighting etc.. will ignore you if you are 60-100m away. Black Rhinos, particularly with young ones, will simply disappear as you get within a few hundred metres. I have been lucky on a few occasions when one large male woke up in front of us and a couple of times when pairs of White Rhinos have been too busy eating. We came across an injured hippo on land and shot him from a fair distance.
If the 600/4 does not work for your budget/style look at the 500PF and FTZii plus TC -vs- the 100-400 -- the ONE issue is the you would need an F-mount TC for the 500 and a Z-mount TC for the 100-400. The BIGGEST challenge you will have is shooting ultra early or ultra late in low light -- this is when lions and leopards are most active. The rest of the day they can be found eating or sleeping. NEXT is the heat and the RAIN (more importantly the impact heavy rains in April/May have on the local roads and tracks in the parks -- but your guides will get you there. I am going now because it is the end of the dry season and hopefully grass heights will be low. You may find heavy grass and bushes. But nice temps. It is somewhat of a lottery when the weather happens and how disruptive it is. Most hope for a VERY heavy monsoon season so that the droughts of previous years can be put behind them.
I would spend some time working out if you can rent or buy a 600mm for your trip. BUT - then since I have my own vehicle/driver/guide I do not have to fight with other shooters for space. Some folk have adapted the sony 200-600 and made Canon glass work well with adapters -- (See Wildlife Alaska on YouTube and others)
I have both a Z6ii and a Z7 -- while the Z6ii is OK - I would probably pair the Z7 as a 3rd camera with one of the shorter zooms for portraits AND so I want the resolution - the Z9 gives me the speed for action. Nothing wrong with a Z6ii --- not many years ago 20mp was HUGE, but now we have 45.7mp. The Z6ii and Z7 both are useful for video and can be triggered remotely via snapbridge.