I used to have a Zodiac Pro 420, granted it was a a 2006 hull, but the basic hull hasn't changed much. If water is getting into the void between the hull and deck, then I'd put my Greek Euros on leaking screw holes, or the bow locker.
The bow locker you can't do much about, but you must be seriously shipping water to need a bilge pump in the void. The old Pro's transom is different, so it may possible to get water coming in when coming off the plane in a lumpy sea.
Regards existing screw holes, it's not a big deal to remove the screws, clean the area thoroughly, then apply a bead of Sikaflex to the console and seat base and holes, then screw the whole lot down again. If you're worried about the strength of the existing screw holes, then you could always fill them in, drill new pilot holes and use fresh stainless steel countersunk screws with washers.
Is that with or without VAT?