Dual exhaust on a single exhaust car

hi my 73 Dart had a very badly made dual exhaust on it so I purchased the summit dual kit but since it’s a factory single exhaust car (I think) the summit kit wants me to drill a hole in the floor to make a hangar. The car has a spot before the axle for a muffler hangar to attach too. But the passenger side exhaust barely clears the driveshaft. So all in all I’m just wondering if there’s a company that makes a better fitting exhaust long tubes back honestly turn downs are preferred. Thanks for any insight.