The bore size on that Pietta (I assume is a Remington Repro) will be either .454 or .457. There is no swaging down to 44. I am not sure why they called them 44's. I have two guns with R&D cylinders and it defies all logic, but they shoot very well. Accuracy at short ranges..50 yards, would be sufficient to hunt with if they hit to poa.
The velocity you mention, 850 to 900 would absolutely handle a white tail deer. I think if you check though, those cylinders are not really meant for that velocity unless you use black powder. They are for black powder or "cowboy" level smokeless. That usually means more like 750 fps. All in all a cool idea, but not one I would try.
When you found a Blackhawk for about the price of a cylinder, that became a no brainer. As others have said, you don't need to load that Ruger up hot to kill a deer. Now THAT is a hunting revolver, one of the best IMO.