True, it would require a bit of fabrication. But keep in mind that the large diameter wheels are a contemporary modification, and wouldn't be accurate to use on something like a 50's style custom, for example. Contemporary cars don't have items like chrome bumpers, split windshields, drip rails, etc.
Of course, you wouldn't necessarily have to go as extreme as something like my coupe design, either. Removing or molding the bumpers, flush mounting headlights and tailights, and a single piece curved windshield along with the right color and stance would make your car stop traffic. Give your car some good detail work, update it here and there, and put some 18- and 20-inch wheels on it.
Anyone can put a wheel and tire package on a car. Making it all work with the theme and feeling of the car is what will make your car stand out from the thousands of cookie-cutter customs that are out there.