what type sling for pardner pump?

[old fart]

i got an allan padded sling and swivels for my pardner pump, well i installed it and its ok over the shoulder carry but i wanted to cross it over so it would keep the gun across my back and its to tight for that. my regular pardner has a shotgun sling that goes over the barrel and stock and its got plenty of adjustment. i thought about taking the shotgun sling and fitting one end over the magazine tube and the other on the grip of the stock as it would be longer that way and may work for me. what type sling do ya'll use? and will it let you put the gun so it rides on your back for better walking? thanks