Welcome to the planet Andy.
70vg would be fine for the AIO. I haven't tried 80+vg in one of them before but I imagine it's starting to get into dry burn and coil gunking territory.
I'd say buy the juice and see how it goes. If it's burning coils or not wicking properly, you can just add a couple drops of PG or de-ionised water to dilute it down until it works.