It was okay to use the standard CZ sight (small bead) on the 458 - it shot spot on without any adjustment. The CZ rear sight base had to be removed of course.

The NECG ghost ring is adjustable for elevation and windage BTW (allen head lock screw that can be undone to allow the ring to be screwed up and down, and screws on both sides for windage - the big headed screw is the one that you use to loosen to remove the sight and the other is effectively a stop).

I also bought one for my CZ550 in 375. It shot way too high with the standard front sight and there was no adjustment left in the ghost ring to compensate for it, so I bought a bunch of Recknagel front sights from Graeme Spraggon in Tamworth. The CZ standard front sight is 6.3mm tall. The Recknagels come is several heights and I bought 7.5mm, 8.5mm and 9.5mm beads (larger than the standard CZ bead) and a 10mm high post. The 9.5mm is the tallest bead they make.

Google the Recknagel catalogue to view the options - I believe Graeme can order whatever you like.

They do require some fitting - basically careful filing of the base of the bead insert. It's a bit fiddly to do but not a big drama in the scheme of things