Honestly having had the 700, model 7 and 2 ARs chambered in 300blk, I'd go with the Handi rifle if not an AR. The 700 is a heavy police profile, much too heavy for the cartridge, also chambering was iffy at times with certain profiles, same with the model 7. Now I'm down to one SBR 10" AR in the caliber. The Handi will make loading easy and brass last a long time and will save bunches of up front cost. The Ruger would be a nice choice as it's light, just haven't handled one to comment.
Option B: if you haven't considered a .38/357/max, it is much simpler to download and ammo is much more common, offers power in line with 300BO on high end. Subsonic 38's are really quiet. Could be had in a single shot, Ruger 77/357 or even a lever gun.