As people answered already earlier, 70/70/70 is used to start NMZ, turn into mains, and sell them as stakers/main accounts.
Related to dragon killers, I think most of them just survive for a few days but start at 60/60/60 from what I've seen.
I got a 78 defence account (hit you on pm) that might suit your needs, but all I can say from personnal experience, is that it just takes way too long to get levels, even when you have proper gear and other related stuff.
Quest reqs takes around 30-50m. (Jungle potion and tai bwo)Shilo Village quest takes close to 30m.
(This is based on an account with fairy rings unlocked)
Congratz on the release, sadly I've already encountered some bots doing these.
You should also look into supporting the downstairs mines, might actually become a very popular script for HC Ironman and Ironman.