Xel Naga has a pair with similar total resists, but with a distribution that is not nearly as desirable(IMO). Although I believe his LRC is higher than yours. The problem you run into is that since Diminishing Returns was instituted for Mana Regen, MR has beome less popular as higher numbers are not as effective as they used to be.
For example when you have 2mr you get 2mr, when you have 12mr you may get for example 1.5 mr per every 2mr. So what this means is it becomes necessary for people to max out their lmc, and in addition really concentrate on gettin mana inc, or other stat mods.
Another point to consider is that b/c of diminisihing returns for MR, it is not necessary to have leather pieces with the mods if you use a HOM and RBC which gives you a total of 7mr.
The mods and the resists distribution/intensity on this piece is quite a rare combination though, and some players do still like to have high mana regen, or prefer not to use as many artifacts. I'ld feel confident that you could get around 50m, quite possibly as much as 70 or 80, but I feel that the recent changes to the game will make it difficult, and lengthy above the former.