There aren't a ton of frame hung rear sway bar options out there to begin with. Obviously the stock ones are, but then you're stuck with stock diameters. Firm Feel sells one, but I have no idea if they can adjust that for a 1/2" spring offset or if the 1/2" offset is really even enough to be an issue. I'm sure if you called Dick at Firm Feel he could tell you. Most of the aftermarket bars are hung from the rear axle (Hotchkis, Hellwig, Adco, PST) and for those the 1/2" offset isn't really enough to make sway bar mounting a big problem. I actually use the Hellwig E-body rear sway bar, #6908, which is a solid 7/8" bar. Hotchkis sells a set of studs for the rear dog bones if clearance to the springs is a problem.
https://www.summitracing.com/parts/hss-17366/overview/
As far as tires go, I'm not really sure what you tell you. Selection for 15" rims pretty much drops to BFG T/A's and Cooper Cobra's once you go wider than a 225. I had a set of Falken Ziex's on my Duster when I was running cop rims, they were 225/60/15's. But once you go to a 235, 245 or larger all that's left for options are the T/A and Cobra's. They're "OK", but neither is designed for real performance handling.
And you may want to figure out your tires before you go to a +1" spring. It may not look like it, but my car actually has about a 1/2" rake front to rear. Pretty much all from the difference in tire height, I have 25.6" tall front tires and 26.1" tall rears. I assume you're running the 1/2" spring offset to run wider tires in the back, but with the tire selection available in 15" rims that means your rear tires will probably be more than a little bit taller with the fronts, especially with only a 15x6" wide rim up front. You may get more than enough "rubber rake" to not need any additional rake from your springs.
Oh, and the rear bushings you'll need for the 1" rear eye on those springs are these guys.
https://www.summitracing.com/parts/ens-2-2117g. You'll still need the standard A-body bushings for the shackle to frame mount though.
Not sure how they're supposed to be "constructed better". The number of leafs isn't as important as the rate and balance between the front and rear sections, and the 120 lb/in rate is higher than the stock A-body XHD springs.
