I for one don't like they way they look, there is something "wrong" about it. I would recommend waiting for the correct wheels. By the way, how old are the tires? Depending on what you read they are not safe after 10 years regardless of how good they look (see the archives).
Back in the '60's I used to run 21" wheels / tires on my '30 TownSedan. They fit perfectly, while admittedly looking a bit 'odd' to the finiky judgement of the trained eye. They gave me a bit more speed and gas milage. Sometimes they would hit a brake rod when turning tightly.
That's what I would do.
It'll keep your car on the road and buy you extra time to look for the 19" wheels and tires.
Then you can always resell the 21".
Welcome to the Ford Barn, my avaitor you see is a truck that I have and I am on a limited income and will never be able to drive it. But I still can have fun restoring it.
A friend bought a really nice, BLACK, '29 Town Sedan, with Straw colored '19's & it looks very nice! Gene gave me a 16" half worn LESTER tire for a spare, REALLY OLD! It has raised letters that say, "TO BE USED ONLY ON CARS MANUFCTURED BEFORE 1948"! Probably something to do with the "safety" rim design, that came In around 1949. That LESTER tire is supple & smooth as a NEW tire!!! WHY?? don't they make tires like that NOW! Bill W.