Nofx,
Congrats with your .458 cz, cz's are great, I have a cz .458 lott (it was a .458 win) I have only mucked about with two projectiles the 400 gr speer and now the 500 gr woodleigh soft which I am zeroed for. CZ's are my favourite brand of rifle for sure.
I would one day like to have a .450 Rigby made on a cz .458, for that I would choose the 550 gr woodleigh.