20 moa base should be fine.
Terminals depend on bullet choice here... a 300 or 350g hard cast is going right through a deer out there pretty damn far... a light for caliber hollow point probably not. Subs at 500 yards is generally tough simply due to SD and variation in the rounds. You gotta really be on your game to get it consistent.
It can be done, but man its a pain in the ass before you start dealing with the drops and wind. It's like you're starting out behind the curve I guess is what I'm saying.
Powder and bullet choice? Need to choose wisely here. Not sure how your case fill is gonna be, and that can play hell right off with shots out there past 400 yards. Will need to find a bullet/powder that gives good case fill.
Inside 300 yards is doable for sure without Hercules level effort... sometimes you get lucky, but i prefer 200 yards and closer for most subsonic stuff, especially hunting... closer is better and what those rounds do best. Expanding subsonic and big wide flat noses do well.