The grand African .458 WM M70 rear sight was paired originally with a 3/32" silver bead,
and I find that will do.
I really look at iron sights as primarily backup to a scope. A low power scope trumps all.
The M70 African reproduction by Wisner can be filed into a flat-topped, square-notched rear sight,
and used with the gold patridge.
I did that 20 years ago on a .500 A-Square:
Hard to beat that, unless it is a peep rear sight with gold patridge front.