Gee, fuel pump “on the way out” in a 7 year old vehicle? That’s a rather piss poor effort from supposed quality factory parts Holden is pushing out… IMO, such is hardly “of durable quality” be it pump failure or a connector wiring failure
At least you’ve likely got an access port under the rear seat which makes changing it much easier as is replacing the ‘unicorn dust‘ fuel filter
Poor VF2’s don’t have such access ports under the seat requiring owners to drop the whole rear sub assembly
Cleaning the tank is always a good idea, especially if you notice crud within… But whether you’ll be able to clean the whole tank via the access panel is doubtful. If that’s the case it’ll require the whole rear sub assembly to be dropped just to clean the 7 years of cruel crud out of it, at which point you’d feel the pain of VF2 owners
As for the pump itself, since you’ve got E85 capability, the pump is designed to handle 20%? more flow than the requirements of running on straight 98RON. So there is a bit of flow headroom if you are only running on 98RON
What that means in terms of mods… can’t say with certainty