Hello YellowHorse,
Agree with Idaho Chris; although there is probably a limited market for such, it would be nice if there was a decent repo for those lug nuts.
The original D0OZ-1012-A lug nuts listed for the '73 Mustang were sourced from the '70 Torino. Oddly, the only wheels on the '70-71 Torino to use chrome lug nuts were the 15" Magnums, and the D0OZ lug nuts were too tall. Ford revised the catalog listing to the correct C4GY-A chrome nuts. The D0OZ-A lug nuts continued to be used on select Pinto, '73-77 Maverick, '75-80 Granada, and sister Mercury vehicles with slot aluminum wheels. They were discontinued in early '95.
The D7OZ-1012-A lug nuts mentioned earlier are as close as you will see in appearance and size in an OE lug nut from Ford. They were released originally for use on the Polycast Road wheels on the '77-79 T-Bird, LTD II, and Cougar. They were later cataloged for the '79-84 Fox platform vehicles that utilized the TRX tire/wheel option and other later models through 89 with various cast aluminum wheels. When the D0OZ-A lug nuts were discontinued, they were not replaced by the D7OZ-A version. The D7OZ-A were discontinued in early 2000, so they have been out of the system for a while and are becoming difficult to find. Of course, when some vendors found out about the Mustang applications, the lug nut that once retailed for $1.50 immediately shot up to $20.00 or more with its newfound fame!
The illustrations below show the difference in the crowns of the two lug nuts and a 1/4" height difference that the untrained eye probably wouldn't notice.
The suggestions on the after-market lug nuts appear to be your best bet.