Well, Musashi was asid to have been over 6 feet tall (huge for a Japanese, particularly in the 17th Century!), so Hyoho Niten Ichi Ryu?
But really, physical size can make it a bit quicker for you to get some skill in applying techniques, simply due to sheer strength, but it has the drawback of leading you to short-cut your way around the technique itself, so if you have to apply it against someone even stronger, you are in a bit of trouble! Most arts, at least those around now, are designed to give an advantage to someone who normally wouldn't have one, so you will find few arts designed to allow a bigger, stronger guy to have even more advantage over the smaller guys out there...
But, and I'm going to say this once more, THERE IS NO ULTIMATE, CUSTOM DESIGNED ART FOR ANYONE!!!! DO NOT LOOK FOR IT, IT DOESN'T EXIST!!!! ANY ART CAN BE MODIFIED TO SUIT ANY PERSON!!!!
Okay, that was a bit shouty, as someone here might say, but I feel necessary. Really, Joab, the most important thing is the instructor and the school, not the system itself. Don't try to pigeonhole arts like this, it just doens't work, and you will most likely dismiss your perfect system without even knowing about it.