First of all, you're not a Charm type and you won't have enough HV. NEVER. Your only chance to survive is lots and lots of LK so you could block hits, and you have Lucky 7 and Aura of Luck so you can increase it even more.
HP is a thing you really need, but personally I'd say something like 15~20k is enough. My lion don't even have that much.
Then, 1 HV is equal to 20 Gun Defence. So you could try using Lock-on, I have that with my sci and it reduces enemy HV really nicely.
I would just say stick to AC LK and HP, HV isn't needed much.
Another thing is if you know how to perform timed criticals, no matter what HV enemy has you can hit it. Use Keen Sense skill and you can land some nifty damage even on strongest enemies (too bad you're not a sci, so you don't have access to Gun Overdrive. Mmmm, Gun Overdrive...