You and me both, parts collection wise! I have parts from my T/A restoration spread out in just about every room in the house at this point.
I'd use a hand wire brush and carefully brush at it to see what you find under the rust. Media blasting is the best way to clean up a casting and make it look fresh but that will take off any original paint or coatings.
Look at the front of the casting and see if you can find the date code, that will at least give you an idea if that is the original one your car was born with.