You haven't stated on the sidearm will be. That will help out alot. As for me, it's a 7.5" Super Redhawk, one heavy pistol, so I wear a uncle mikes shoulder holster. Sometimes I forget I am even wearing it during my trips. You want a holster to distribute the wieght in various places so to prevent fatigue in a 1 spot.
Good Luck in your search.