I have to say no, not a flower car, not any more than a Chevy El Camino is a real flower car.
I truly do find it interesting that whenever I'm talking to someone about funeral coaches, I mention "flower car", they get a weird look on their face and I have to explain what one is. Yet it seems like every time someone has a home-brew Cadillac or Buick or Lincoln or whatever "El Camino", they claim it was a flower car.
People have been modifying cars almost as long as there have been cars. The Great Depression saw alot of luxury cars cut down into trucks, simply because there wasn't money to actually buy a truck. World War II and immediately after saw more of the same, simply as new vehicles weren't available, so people did what they felt they had to do. But I don't think any of those conversions were claimed as, or got mistaken as being, flower cars.
And ever since, there have always been the people with a blow torch and a few six-packs, who thought they knew how to "improve" a car, and usually an older luxury car was their innocent victim.
And let's not forget the 1970s, an era of questionable automotive atrocities taken out on innocent sheet metal, where there was a fad for awhile of taking brand new luxury cars, and making them into El Camino-style vehicles, with some of those conversions even being factory authorized. Yet even those were never advertised as being flower cars. They were rich man's pickups.
Any car can be cut down into a pick up, and probably just about everything has been over the years, but being a car-based pickup does not automatically make it a flower car.