i dont think you can convert flops to CUDA cores as they are two different thing. "Flops" is the number of floating point operation per second. so a card with 1 Gflops can do about 1 bilion floating point operation per second. so generally Flops indicate the cards compute power.
Cuda core on the other hand is nvidia's fancy name for shaders or stream processors. you can't convert a cards computational power to the number of shader it contain's.