Contact some folks in the Florida Model A clubs, and see what consensus you get from them.
In general, the number that appears on the title should be able to be found on the vehicle.
I would think that what you have in-hand is close enough to satisfy most Model A guys when it comes time to sell the vehicle.
Most DMVs are not experts in antique car taxonomy, and are not particularly interested in "Helping" the hobbyist.
I've run into my share of DMV clerks who insisted that the only acceptable number for registering a vehicle was the 17-character Alpha-Numeric "VIN number". They weren't interested in hearing that my vehicle pre-dated the VIN system by 30-some years.
If you go asking to amend your title, the state will probably insist that you take the vehicle to a State Police garage, and have a State Police inspector verify the frame #, which means removing the body of the vehicle.
And before doing that, I 'd want to be sure there really was a serial number still visible on the frame.