I'd not try to make a Cadilac with Volkswagon parts. I'm positive a .44 would be preferred, and a .45 would be better yet.

Homer's .45 M92 Winchester is MUCH superior to the Ruger bolt gun for fast and fancy shooting.

A companion same calibre handgun would be a Ruger DA in .45 Colt. Even with a silly 38" twist, the .45 Colt will accurately handle 340gr. bullets better than the .44 mag. does with 300's. At least my WW in .45 Colt was much more accurate than my Marlin in .44 mag. with all bullet weights. The reverse is usually the norm- with Marlin being a much more accurate rifle, no matter the chambering.

I wonder if that action is big enough for a .500 S&W chambering? That would make a really useful rifle, but I'd not even consider it in a handgun.