I built the headers on my car ,, not a crown ,,it is not especially difficult but it is time consuming ,, but if I needed another set (of custom ) I would pay a fabricator to do them .. first choice would be to search various header manufacturers to see if they catalog anything that looks useful as is,, would not be original looking tho ,, hardest part of building my own was figuring out routing of the tubes ,, if you have original set then you can just have them duplicated and that is easier ,, I googled for "custom exhaust header fabrication in Missouri" and several shops came up ,, here is one in St. Louis ,,
http://www.classiccarstudio.com/speedsh ... s-exhaust/custom headers are expensive ,, professional time is not cheap ,, so it comes down to how original you want the car to look ,, cast iron exhaust manifolds are inexpensive and quieter and seal well ,,, try searching for a street rod shop near you and they will have a fabricator ,, a regular muffler shop wont want to mess with
it ,, good luck and let us know what you come up with
a little searching and I found where Mike Levine put out a feeler a few years ago to see if there was interest in getting Crown headers reproduced ,, he figured he needed interest in 10 sets to go forward ,, don't know if he got it ,, anyone who needs a set should get in touch with Mike to let him know if there is a demand