I haven't read any of the other responses, just the OP.
I'm a huge diesel advocate and even I think you have enough truck to tow 14k. 4.10 gears will work very well and the Triton V10 is one of the rare gassers that will hold up to towing big weight. Sure, you spin a little high and chew through some gas but it'll get the job done. In fact, you'll likely be delighted with the combo. Your F350 4x4 LB SRW is a whole lot of pickup.
I wouldn't modify anything or see the need to do so. But check your brakes are well maintained and that your tires are E-rated and to the proper pressure and tread depth.
