If you're interested in red & white Simmental cattle, I'm afraid you'll have a hard time finding a good bull, whether you're looking for a bull to buy OR a bull to AI to. The serious breeders will always evolve with the market, and when the flowered cattle got impossible to sell, most breeders eventually changed their programs.
Fleckvieh cattle do have something to offer, and you will find those color patterns in those full bloods. The type may not be exactly what you're looking for, and if that's the case, I suggest you think about red or even black baldy or blaze-faced purebred cattle. Mating baldies to baldies will produce the color pattern you're talking about, not necessarily every time, but more often than you might think. You may even get white legs or belts out of two solid, blaze-faced parents. If you can identify carriers of the spot gene, mate those cattle to each other and you will get the colors you're looking for. My theory is that most if not all Simmental that have some white in their faces carry a spot gene which is a recessive gene.