Centerline front runners on my 73 scamp????

I have a 73 Plymouth scamp 5x4 bolt pattern drum brakes. I bought centerline front runners 5x4 as well. They fit, but a shop told me that the wheels have minimal contact point on my drums, I guess meaning it's not flat or flush? Can I still use these? He speculated they could be for disc brakes 5x4. Is there any way around it, or is he wrong? Help help