There are some +P loads available you will need to steer clear of...
Buffalo Bore Heavy 45 Colt +P Pistol and Handgun Ammo , BUFFALO BORE'S DEER GRENADE 45 COLT +P and Hornady Critical Duty .45 +P Ammunition
Heavy 45 Colt +P Ammo is NOT for use in your Uberti Yellowboy.
As stated any factory Cowboy loads are fine , Brands include Black Hills, Magtech, Ultramax, TenX, & Winchester USA Cowboy Ammo 45 Colt