Mesa Tactical makes, IME, 100% good stuff. If this is the config you want, there stuff is good generally. I live by their sling loops, mostly inappropriately modifying them to bolt to rifles and carbines, where I find they are very solid metal.
For a much cheaper options for the AR receiver extension style, look at the FAB Defense options. I had one, shot it a good bit, very solid despite being very plastic. Also briefly (1-2 tubes) fired a few others, including something that tilted the receiver extension tube down to simulate a shotgun stock drop. Hated that.
It was the low one, where you'd more expect it instead of the dogleg up as above. It was still crazy high. Possible but unpleasant to use even pretty high irons and even RDS needed a riser for me to be comfortable.
I think that high rail on the receiver is a clue for the High Rise. If you want an RDS for sure: maybe. But think about fitting it into places shotguns get stored, about now having to remember mechanical offset for the shotgun.
The recoil force even for straight line stock adapters like I had is not bad, maybe improved for muzzle rise but it tends to also therefore put all the recoil back straight at you, AND the receiver extension is metal so none of the flex you get from a hollow plastic butt; think more like wooden stock recoil force instead. I am sure the High Rise is even less muzzle rise as it makes sense but it's awful high up there. I also have concerns about how far back the pistol grip is, and my middle finger resting on whatever the extension block is made of. Hmm...
(FWIW, I did the
Hogue overmold as they have a short option and I was feeling lazy at the time despite shortening like half a dozen Mossberg stocks and sanding the recoil pads alone; still had to install a sling loop and... somehow I have no shots of the finished gun to share but ask if interested for some reason).
ETA: Safety! On the 590 your safety is up top. CANNOT be reached usefully when in any firing position. If you want any pistolgrip buttstock and to use the safety, trade for a crossbolt safety gun.