I have been buying and re-barreling, re-chambering, and fixing up CZ 550 Magnums since as soon as they showed up on this side of the pond through CZ-USA, about the turn of this century.
Sadly they are no more around here.
The initial issue .505 Gibbs and 404 Jeffery required a lot of work and it wasn't until about 2007 (like in catalog link above) that CZ-USA started getting their act together.
Guided by things like replacing my broken marble cake stock on the mild little 404 Jeffery,
they soon started putting the usual double cross bolts in them instead of none, or just the single one behind the tang.
Even after I had an expert gunsmith glass bed, and install pillars and crossbolts.
The pretty .458 Lott of OP has a glaring deficiency IMHO:
The Talley rings with the double hole drilled above the recoil tab on the rear ring.
I have busted them on hard kickers, and quit using Talley CZ rings altogether after stripping the main mounting screws on another set,
and googled up some images on the internet.
poor focus but the crack is there.
Some other images by other people:
I thought this version (no holes above recoil tab) was improved, but when I kept it tight, fearing loosening was what caused the other to fail ...
... levers pointed above bore axis when on right side so that recoil keeps them tight
... my puny fingers stripped the main mounting bolt, no cheater pipe involved:
No vertical split ring can be as strong as a horizontally split ring, where the scope-tube-holding function is independent of the ring-to-action-holding function.
The OEM CZ 550 Magnum rings are as strong as it gets, especially if you replace the main mounting screws with automotive socket head screw where the QD lever becomes QD itself, and is carried in your pants pocket.
Or Bubba your own QD levers onto the OEM CZ rings:
On the left side of rifle, levers point downward to have recoil keep them tight.
The .500 Jeffery above is waiting for Bubba to sand down the epoxy build on the fore arm edges.
Barrel was so fat the CZ laminate stock's barrel channel had to be enlarged.
Bubba plans to cover the entire mess of the stock with grey truck bed coat, rugged texture paint to cover the checkering and all.