Your Z6i is just about perfect for a .375 because it is ideal for almost every environment. At lowest setting you can use it anywhere a red dot or even open sights would be appropriate, and yet you have the magnification to fully take advantage of the .375's 300 meter range envelope.
All of my 30-06 class rifles (8x57, .270, 7x65R etc) carry a 2.5x10 x 42 of one form or another. Most are Leica but I also own Leupolds and Swaros.
I should also admit that I am a bit of a Luddite when it comes to ballistic turrets and the like. I have yet to take a shot at a game animal at a distance where such is required.
So from an optics perspective, you are halfway there.
A word of caution about open sights - particularly for dangerous game. Very few people today have much experience in the use of open sights on big game. As a client, hunting a buffalo let's say, you have exactly one overriding responsibility - put that first bullet in exactly the right place. Screw that up and everyone can have a really bad day. I spent a career playing with iron sights, but even in thick brush, a scope makes putting a bullet through a narrow window or sorting out the correct shoulder of a group of three bulls lounging in the shade, infinitely easier. All my DG rifles are scoped except for a Birmingham .470 (which, sadly, I have yet to use on a buff - and frankly, may never do so).
Do indeed have a good set on your DG rifle. However, I would consider them for follow-up in case something did go wrong with that first shot.
And please do not consider this a criticism of the use of irons per se by those hunters who have developed the skill set to use them effectively, and the self-discipline to walk away from the many opportunities that could easily have been addressed with a properly scoped rifle.