I pulled an 11' disk with a Minneapolis Moline 670 - 70 hp tractor w/o dual no problems. The 14' disk was pulled with an International 856 - 95 hp using duals. Remember we were putting in around 1,000 acres of row crops a year. You can take some time and make several shallower passes to help with breaking up the ground finer & knock down the high points while filling in the low points. I think you would be able to make the 14' disk work for you. As mentioned previously, let the wheels carry part of the weight as needed.
If your are working freshly plowed ground, you want to be able to pull the disk fast enough it will throw dirt. You will also be needing to make some diagonal passes to help with the field leveling.