I can't help with the radiator shops in that area, but I am assuming that you want to keep the old tanks for originality. If that is the case then just taking it to any radiator shop and have them put in a new core will not keep the originality on the radiator. The cores come with the top and bottom supports, and you probably will not be able to save your original supports, which are unique on our vintage big blocks. You might want to look at a DeWitt core which is original and any competent radiator shop should be able to remove your old core and put the new core onto your existing tanks. Here is a link to DeWitt's website.
http://www.dewitts.com/pages/product...asp?ProdID=262
If you are not concerned with originality you might also want to consider a DeWitt aluminum radiator that replaces the old Copper/Brass radiator and it has similar appearance to the old radiator.
I hope this helps!
Rich