Bumping an old thread. Great article. Just used this today. I bought my switch from Oriellys.
Interchange says It is the same ignition switch as a 1971-72 cougar, among a ton of other cars. Check the fitment tab on the site.
A couple places had it cheaper, but these guys had it the next day for with free shipping.
https://www.oreillyauto.com/detail/c/standard-ignition/standard-ignition-starter-switch/std0/us67/v/a/15254/automotive-truck-1971-ford-ranchero