I think better is 8:1 or just from 50 to 60lv add only str then go full int because the passive already gives you a hp bonus

im 72lv i made from 60 to69lv full str now ill go full int and i got a clear around 6800Hp (without eny str or hp on the items).
Btw adding from 60 to 70 lv is better because the hp you get from each stat depend of the lv you are...but dont make it from70-80 or80-90 because yuor magical balance will sux..yes you will have around 86% magbalanace at 70lv but at 90lv it will be 90+ 100%
And one reason to make it full int or 8:1 isthat you use spear wich make highter dmg...