For many years now, Jerry Jones has made great Danelectro replicas. I just googled the site and find that Jerry Jones has retired and ended production, but there's still instruments in the channel. It seems like it would be worth giving their business office a call and see whether they still have a Longhorn case or could connect you with their supplier.
You certainly can get a G&G case for a Longhorn. This company is the maker of most high-end Fender and PRS cases for many years and most of the Alembic cases I've seen look like G&G as well. They'll have the patterns on file, you just need to find somebody to order it though.
Personally, I would go to Ed Roman only as an absolute last alternative. Try googling his shop to see what sorts of experiences people have had. You don't need to see 10 bad reviews to stop considering - when you find 100+, that ought to mean something. There are lots of builders and people in the community at large that will help you out if they can.
David Fung