I have a bud who has had JD do several Cuda dashes and they all turned out very nice. I heard several different stories about usable cores lately, so I just called them. Here is what they said.

They use the core you send them, period. They can fill 3 speaker dashes, fill ac vents or cut them. They will charge you for this extra work. I did not ask about the Cuda to Challenger conversion. They will put a 70 script in a 71-74 core. They completely strip all the old foam from the steel core and hand lay new foam and contour it to the correct shape. Then they vacuum form the correct vinyl over the foam. The steel core is all they use and it must be rust free. I was told years ago that the better the core you sent, the better the finished product. I think years ago they might have left some of the original foam in place, but I asked two weeks ago and he said they strip everything off now. You will be happy with a dash from them. I'll pm you about a core if you need one.