As an Aussie who went to the US and spent some time driving around, I got an International Licence here in Australia (NRMA/RACV/ETC for around 35 bucks), I also took my Australian driving licence across as well. I got pulled over and showed both to the cop and had no dramas. I would also carry my passport as well just to be extra sure.
I would do a search on the web, I remember looking years ago and there was not very much for that price. My crappy looking 66 Coupe cost 4500 US dollars and she needs paint and a few small dings knocked out.
Depending on which state you are going to visit (California & Florida), why not try an hire a new 2002 Cobra for a week or so. Bound to be more fun and comfy than the old 67.
Used to be Mustang1966coupe.
66 Silver Frost Mustang 289 Windsor
71 XY GS Fairmont in Bronze Wine 302 Windsor
92 EB XR8 302 Windsor
Sure do love those Windsors