Growling Disc Brakes

Just converted my 65 Dart Gt to disc brakes up front. First attempt in the driveway using the brakes produces a heavy growling sound. Is this normal for new disc brakes? Am I just over thinking that there is a disc to pad problem. It was an SSB conversion kit used. at to try it on the road?

If the pads are new, go out and break them in, that noise may very well go away, if it's the sound I'm thinking about.