CR 500,
Yes the big Brno action has been used in many custom rifles and has also been used by big name makers.
They differ from the 98 Mauser in several ways, most notably in their ejector and trigger systems.
They are closer to the design of the original pre 64 Winchester than the 98 Mauser.
The early peep sight actions are supposed to be of better quality than later Brno's but after owning both types I'm not so sure on that issue.
That said I'd rather have the earlier peep action as I happen to like peeps.

The action has many plusses as far as big game rifles go.
It also has a few things that will need some "fixing".

The 5 shot drop magazine is sometimes a bit too wide and this allows cartridges to float back and forth when the bolt is closed.
On a big banger this can hammer the hell out of soft point ammo during recoil.

The bolt, even on the peep actions can be a bit "draggy" and can do with some lapping and smoothing and also some attention is needed regarding the ejector spring pressure.

The safety works ass about face.

The "single set" trigger is not much chop on a big gun so hopefully you also have the standard trigger as well.

The integral 3/4" scope dovetails limit the type of mounts you can fit, and also depending what mounts are used, you may have to organize some sort of recoil stop for them.

The bolt handle requires a higher than ideal scope mount especially if the rifle is stocked to use open sights.

The knife edge extractor notch cut into factory 375 and 458 barrels can play havoc with cartridge feed on the big blunt round nose soft point bullets.

These are a few things that I had to address when I built a semi custom Brno 602 458 Win Mag.
They can be made into a very good big game rifle and I really did like mine.
Thing is I like doubles better and it had to be sold.