One of the main benefits of a 1 defense pure has always been high HP. With the state of the wilderness, and the wide range of attackable levels in PVP worlds, in my opinion, it doesn't make sense to limit yourself if you only have one pure account. If you're multi pking, staying low level is even less desirable (to an extent). I think the best CB lvl is between 75-80 for the most competent and fun pure build. 90+ str and hp, 95+ range 99 mage.
Of course, just my personal preference. But back in the day, pures basically needed hp when fighting def noobs, take a lot of hits and pack a big spec that can nearly one hit the low hp def acc.