Custom pans are easy to build for a Mopar big block since the pan rail is flat. I have CAD files for the pan rails so when I had Charlie build my pans I would send him the billet rails. I had a local water jet guy cut the rails out of 3/8 or 1/2 inch aluminum plate for Charlie. If you go that way talk to the builder since they'll most likely want a soft sheet aluminum not a hard billet aluminum. I think Charlie always wanted a 5005 aluminum but I'd have to look at my notes.