I myself went zerk (currently maxed zerk quit playing it now, was on the road to 99 attack which I regret and always wish I stayed 60). If I were you even though it seems so tedious I would keep this account your pure, if you want to PVM make a seperate account and get high defence on that. You'll regret going over 60 attack or 1 defence.

Do ags pure !

Stay as a pure to pk, zerk pking is boring with only dds and 75 attack is too high cb, you'll only be fighting ranged tanks/dhers. If you wanna pvm, create a main. Pures and zerks are not that ideal for pvming.

Definitely stay as a 1 defence pure, maybe you won't be as tanky but you will do more damage and even if you don't win every fight I think you will have more fun. Also you'll be more useful in a pking team