I have a Model 70 in 458 Win Mag and really don't like the open sites Winchester puts on their Safari Classic's. Would it be hard to install a quarter rib with an express site that would let me retain and utilize the existing front site? Costs?

I have put Ruger quarter ribs on several Mdl 70's the last being on a .338. Utilized the factory ramp and front sight. Requires drilling and tapping a couple of holes and a hole for the blind pin to fit. Simple install. Don't remember which Ruger rib I bought but the rifles looked and shot well. I've done 3 this way. A .338 and 2 .375's.