Welcome to the forum. We're gonna need a few more details to help you out....year of bike, RGC or RGU, budget etc. Which BN kit did you get? Are you referring to DVD as in you want to play video on your bike (cool in a parking lot, very bad idea going down the road), or are you just talking about audio CDs??????
Bottom line, if it's a pre-Rushmore bike there are plenty of good single din head units out there, Sony and Kenwood are probably the 2 most popular. If it's a 15+ bike there really isn't much of anything available that maintains the features of the boom box that will fit without some alteration. Sooner or later someone will make one, but nothing readily available that drops in right now.