You may have to order your 458 Lott brass. Try www.huntingtons.com or www.midwayusa.com. In the mean time you can use 458 Win brass/ammo.
A friend of mine has a 375 CZ. The sights look crude from the side, they are big and bulky looking, which means they are strong,

but when aiming they are fine.
Good luck on your new rifle.