I had a look at the application form for license plates and it looks like the cut-off year for YOM plates is 1974 so this car would not be eligible.They don't make reprints, you have to find an original. If you care to match the county she lives in with the plate number (she lives in Dade County?), then the first number indicates that (for example Dade is 1-xxxxxx). Here are a bunch of 1975 plates, same guy I got mine from:
1975 Florida license plates for sale
felix2.com
And for example, here is one from Dade county, registerable, and correct for the weight class of your car:
https://felix2.com/inventory/13/1301/1301775140.jpg
There are other meanings to the letters on the plates but I can help with that and if you choose to get one I can help with the application process, but you have to get a regular plate registration first (do the light blue Antique plate as it is cheaper than a modern plate) then apply and swap with the YOM one, it costs about $50 more.
Here's the text:
(4) Any person who is the registered owner of a motor vehicle as defined in this section and manufactured in the model year 1974 or earlier may apply to the department for permission to use a historical Florida license plate that clearly represents the model year of the vehicle as a personalized prestige license plate. This plate shall be furnished by such person and shall be presented to the department with a reasonable fee to be determined by the department for approval and for authentication that the historic license plate and any applicable decals were issued by this state in the same year as the model year of the car or truck.
