Longer wheel studs?

Anybody know where to get longer wheel studs for a 70 Dart? With the wheel/ tire/brake combo on this car ,I needed to run 1/4" wheel spacers. Now the studs need to be a little longer...1/2" would do it. Would consider changing to 1/2" thread also.
Any part numbers would be appreciated
Factory disc brake rotors and original 8 3/4 rear....
Thanks....Pete