If you don't mind something other than a standard Maverick emblem, the old Ford Ranchero steerhead emblems look pretty close to the steerhead on the Maverick emblems. Just a thought.
I'm not sure how big they really are. I have a Dearborn Classics catalog that list them for 1968 thru 1971 Rancheros. Their website is www.dearbornclassics.com if you want to check them out.