Trying it in a 75 is just insane. Neither of those fish belong in a 75 let alone both. But you already know how that turned out.
As far as the 265, is it the 7 foot version? Either way, you MIGHT get away with it if both fish are small, approximately the same size, and added together (after qt of course). It's not a gurantee so you'll have to keep your eye on it.