For many years I ran the 21" wheels/tires of the 1928-'29 Ford, on my 1930 TownSedan. The looks are MUCH closer to the correct 19" wheels/tires than the radically different 16" wheels/tires that a great many Model A owners are using. You will suffer less 'questions & answers' about your 21" wheels/tires than you would from 16" V-8 wheels.
In my years of driving my 1930 Ford TownSedan with 21" wheels, I found three things different from the 'correct' 19" wheels:
#1 - The tires were prone to hit the brake rod when making sharp turns.
#2.- Understandably, my gas mileage increased noticeably.
#3.- The 'look' of the 21" wheels on my '30 TownSedan was not significantly different than the 'look' of the 21" wheels on my '29 TownSedan.
I would recommend that you give these 21" wheels/tires a try. I think that once you get past 'what everyone else thinks', you will like them.