Send the booster out to get it rebuilt. (I do not recommend 'exchanging' it) There are several places that do these rebuilds for around $150.
Be sure your master cylinder isn't seaping fluid into the booster, lest you'll need to do it again soon.
Mustang Corral:
http://www.ebay.com/itm/370320085162?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AITBooster Dewey:
http://www.boosterdeweyexchange.com/These are the two sources I have found & have them in the "hold" till I get a little closer in "need" for assembly.
Maybe others have comments on quality in the concours "finish" about these sources I mentioned.
As far as I understand about the 67's is that they are simply painted BLACK, and I believe it is the same on the 70's too.
DIY rebuild kits for the master cylinder and proportioning valve are available, perfect time to do those while waiting on the rebuild job.