Hey Anthony R, you're fishing in places that I used to fish. I can't help you with the Kastking reels, as like Garboman, I've used ABU's for a long time. I own many, and most were made in Sweden back in the 70's. I only know of one person who's using a Kastking, a fellow on a bass fishing site, and like you he's new to it. He's having his share of problems too, but I don't know if it has anything to do with the reel.
I very much agree with Garboman, that the 5000 size ABU is a good size. That's a reel that will hold about 200 yards of 12 lb test mono, which is how many of the baitcaster reels line capacity used to be rated, based on mono. That was before the braids that are popular now. So, for the fishing you're planning, if that size 40 reel will hold 200 yards or there about, of 12 lb mono, then you're in the same ball park.
I will also say this, the rod also makes a world of difference with the casting setups. I use the majority of mine for lures. When I've tossed baits, it's often been with a larger size reel, such as the ABU 6600 and I like a longer rod, around 8'. Silstar has made some very good rods over the years and, has also made rods for other brands, but not all of their rods are ideal for all purposes. A 7' rod is a good length for the area you're fishing, particularly if you're tossing lures.
Like with spinning setups, one size doesn't fit all purposes, and depending on exactly how you plan to fish, what you're looking to pair up, may or may not work well. The only way to know, is give it a try.