I'm thinking of going the same route (DD)There are only a few choices as far as the Bezel. DD mods dont do them anymore so you can modify your own or buy one from Vettenuts or metra. The vettenuts one is much nicer than the metra but about $100 more. AS for a head unit I'm thinking of going with the pumpkin Android head unit.
Dude metra sells a replacement bezel for the C5 to actually fit a ddin in. The issue you're running into is that the cheap junk radio you got isn't industry standard size. And why didn't you buy the harness instead of cutting it?!?