My personal limit...would be a 475 Linebaugh, in a Freedom Arms Single Action pistol; though the pistol costs well over $2,000. The SA's tend to roll the recoil upwards in you hand --- while the double actions --- tend to push the recoil straight back into your hand; while also pushing upwards.
I have a DA, 454 Casull/45 Colt, Ruger Super Redhawk pistol, with a 7 inch barrel. For the big bore loads...you'll definitly need a padded shooting glove, for your firing hand. It is a wonderful sound...hearing my 454 report, {amplified shooting muffs with earplugs} echoing along the hills above our shooting range. I limit my 454 shooting sessions too a 20 round limit. Magtech seems to sell the cheapest full power 454 factory loads.