I would just purchase the lug nuts off ebay, because you can find them fairly cheap. Like these...
http://www.ebay.com/itm/LUG-NUTS-BUL...95e0a2&vxp=mtr
That being said, rally wheels were not offered on 67-72's, just good old steel wheels, so not sure how scrupulous you would need to be on original rally wheel styled nuts. You could get the threaded nuts with caps, but I think plain old acorn nuts look best.