Depending on what kind of pking you do, any range level may be suitable. If you're going to mage bank, I wouldn't try to show off with 72 range, unless you've got a few good friend around who can kill any person who may or may not kill you

However, shooting for 80-85 range isn't the worst thing you can do. Just remember to bring rune arrows, and you'll do just fine.
My friend occasionally goes to MB 1-2 iteming with a mage short and 25 or so rune arrows..He's around the same range level as I am (he's 82) and he hits 21 or 22 with msb and his outfit, along with a range pot I believe. He's able to pick off some of the one itemers, or the people who are out there to loot without a problem. Like I said, it all depends on what you plan on doing
