For floor pan replacement pieces there are several sources including Year One.
Try Auto Body Specialties, out of New England.
http://www.autobodyspecialt.com/
They have excellent replacement panels.
The company website has a nice catalog feature that allows you to look at the drawing for the actual part, with the dimensions listed.
Also, Hardin's out of Ohio (or could be Indiana) has floor pans for A bodies.
Sherman Associates is another body panel vendor.
If you can wait until some of the Mopar car shows in 2007, you can call any of these vendors, and have them bring your panels to the show, saving the shipping costs.