Yeah i live in Northern NJ right on the NY state line so i hunt in Orange county, NY, which is rifle, and have only hunted there. All of NJ is shotgun only, and i do have a Remington 870 12 gauge magnum set up for slugs, fully rifled barrel with a cantilever sope mount. Nothing beats a good rifle, although many of the sabot rounds for shotguns are true 200yds capable, the rifle just points and carries much better.
Remington has two 35 Whelen factory loads, the 200gr and the 250gr, as i said go with the 200gr for deer and even for just plinking as it wont recoil as hard as the 250grainer. Good luck with your bro's rifle, its probably a Remington 700 which are good shooters.