I've got a Brno 602 in .458 Lott . . . What about strengthening the stock? I've read about putting crossbolts in...
Some manufacturers of good rifles don't really understand what it takes to make a good HEAVY CALIBER rifle. Crossbolts are a really good idea. My Zambian PH had a couple of older Brno rifles - the ones with the pop-up peep sight in the rear receiver - and I spotted hairline cracks in BOTH the .375 and the .458.
Neither one had crossbolts.
The problem is that under recoil, the wood on either side of the magazine box will have a tendency to flex outwards - this causes a tension in the wood ahead of and behind the magazine box, which leads to cracks. Crossbolts in front of and behind the magazine box do much to alleviate this.
Also, a "heavy" rifle shouldn't depend only on the recoil lug at the front of the receiver - there should be another one on the barrel, six or eight inches ahead of the receiver. I like to glass bed both lugs, the barrel between them, and the receiver, leaving the barrel ahead of the barrel lug free floated. (But the barrel channel glassed.)
Sometimes a piece of quarter or three eights inch allthread is epoxied into a deep hole drilled and tapped through the wrist area of the stock.
As far as stock brands, I don't have enough experience to advise on which synthetics are best. I do know that Bell & Carlson started putting a steel reinforcement in the recoil lug area of their stocks meant for "heavy" calibers. (OK, B&C is not the most highly regarded synthetic stock maker, but the one I put on my .30/06 works fine . . . after some fitting & bedding to refine the "drop in" fit.)