If she's free you might as well see what she produces. Make sure to compare dressout percentage and bone to meat ratio rather than just size of the offspring at butchering. Flemish don't contribute much to meat rabbits because they have larger bones, reach weight slower despite larger final size, and tend to take more feed to get to the same weight. Crosses can work if they got good characteristics from the other breeds in the mix but you want to watch for those things dragging down the quality of your meat rabbits.