Those rims will be fine for the car, and 40 offset will look great, but those rims are “borderline” for the width of the tires.
A shop may be hesitant to mount 265 wide tires on 8.5" rims, because max recommended tire width for an 8.5" wide rim is only 255 wide. By the book anyways. If you come in and out of corners like it’s track day, then the possibility exists that the tire can kinda deform sideways, because the contact patch of the tire will be somewhat ballooning/bulging out of the rim. I personally think this effect would be borderline zero in your case, BUT, if you do corner hard, then I would definitely be certain not to overinflate the tires because being overinflated could seriously effect your cornering grip while your contact patch is already in this moderate “balloon” situation.