Well, I may be thought of as a "blasphemer" here, but I have always liked the Weaver rings and bases on such rifles.

If you drill and tap for 2 #39 bases and then use the Weaver rings with the double sided ring caps, you have a system strong enough to handle a 50 BMG and you get your choice of low, medium and high rings.
You can get the bases in steel too.
I know the CZ rings and their copies are very strong and retain zero when taken off and on, but the Weaver is just as strong (contrary to popular belief) and just as repeatable, and you don't have to have a neck like a giraffe to use them.