I love my NEF single shot 30-06. I think you'll like the H&R. My worry would be the Bushnel scope. Nothing wrong with the high end Bushnel scopes, I've got a Bushnel Elite 3-9x40 on my slug gun and love it, but the cheap Bushnel scopes are a waist of money. Get the best scope you can afford.
200 yards? Well a 20 Ga. has more range than a 12 Ga. If you're looking for 200 yard range, I'd start out with a variable power scope. 3x-9x is pretty good, I would want my low to be no more than 4x. I'd want to try a variety of slugs and find the one the gun likes best. Sabots have longer range but have issues with the sleeves that can cause what I call fliers. The sleeve breaks and the wad and bullet go off target. I've seen them with 2" groups at 100 yards and then miss by a foot shooting from a led sled. I've heard the Hornady sabots are better, but haven't tried them yet. I stick to shorter range Breneke Gold slugs in my 12 Ga.
That old slug gun I'd retire. Choke tubs take a beating with slugs. After awhile, they'll change shape and wear out. If it's been wild for awhile, the barrel and threads may have changed shape and been weakened also. As a choke tube goes, so does accuracy. Sounds like your choke tube has been worn out for awhile. I'd at least throw the old choke tube in the garbage and get a new one for shot. (no more slugs) If it's nice and clean and you have trouble turning a new choke tube into it, retire the gun. After 30 years, it's earned a retirement. It's not worth the risk of blowing off a choke tube. Do't take my word on it, take it to a gunsmith and get a professional opinion. 30 years ago they didn't have the ammo made today and barrels didn't need to be so hard. Many of those shotguns were damaged the first time steel shot was used. When an old barrel goes wild, it's time for a new gun.
If I'm not mistaken, you can get a bunch of different barrels for your new gun and they're fairly cheap. A heck of a lot cheaper than TC. My NEF is 19 years old now and if I'd put a notch on the stock for every deer, there wouldn't be much stock left. lol my Handi Rifle was about $160 back in '90, what are they going for now? Was thinking about a stainless steel one.
American by birth, hunter by choice.