If you want an old English African-style "Big Game" rifle, the CZ 550s & the BRNO 602s provide a good foundation for such a project. You might want to check out the 375 H&H webpage to see what can be done by a 'smith specializing in these rifles.
As to your sight question, the 3-leaf express site is fine, it's the front sight that you may want to replace with, say, A New England Custom Gun barrel band front sight. This unit has several different front-site height options, including a low light/nightsite like the British used.
The problem with the CZ/BRNO stocks isn't so much the wood per se, as it is that hog-back shaped buttstock and cheap recoil pad that does virtually nothing to dampen recoil. You could either replace it or have a 'smith reshape/recut the stock's pitch, and fit a Pachmyr Old English recoil pad to it. Both are major improvements on the handling & shootability of these rifles for major magnum calibers .375 and up.
Mine's a 602 in .375 H&H, and has been re-worked along the lines suggested above and for less money than you might think. And while these rifles are good shooters out of the box, they improve markedly to excellent, sometimes MOA, shooters with basic things like proper bedding and smoothing out the trigger. Mine is very accurate with factory and handloads. The BRNOs employ a drop-box magazine holding 5rds, plus 1 in the chamber. 6 rds of .375 H&H is truly "big medicine" for anything I'm likely to hunt on this planet.
If the .416 interests you, go for it. It all depends on what you want to get out of the rifle. The American-style, nonhog-backed stock will probably handle better, and if you're purely a scope shooter, then maybe that's all you'll need. Personally I'd want iron sites on a heavy recoiler (again -.375 & up) for several reasons: they generally aren't used as 300yd varmit guns; scopes can & will break; and for close-in, brush or woods hunting, especially on dangerous game, you don't want a scope anyway.
