: I have built 2 Yost kayaks. I am 6-3 with size 13 feet. I am very uncomfortable and have no room to move or put my feet.

Yost boats are excellent designs, but they're not custom-fit to the paddler the way a traditional SOF boat is.

Foot room is different in SOF boats. You need to set the foot brace position far enough toward the bow that you can angle your feet forward substantially, which creates ample foot room even in a small boat. Again, this is part of the traditional SOF building process. The tendency for paddlers new to SOF boats is to fight this and try to set them up the same as they would a larger commercial boat, but you simply cannot do that in a boat that's closely fit to your dimensions. You have to adapt to the new position. It may take some time to develop the additional hamstring flexibility necessary for paddling with relatively straight legs, but I found the angled-forward foot position to be comfortable immediately.

: I also feel very top heavy and tipsy.

That's normal until you paddle the boat enough to get used to it. If you've been paddling larger, more stable boats, your body is used to making relatively large shifts in order to control it. A less stable boat requires more subtle control and it takes time for your body to adapt. Once you do, your other boat will feel as stable as a couch.

: But if I where smaller they could be great.

Of if the boat fit you better, which is something that should occur automatically when you use traditional measurement and construction techniques.

: I built a expedition single,very nice boat but maybe a
: bit to roomy.I am just starting a Hybrid Night Heron and I will
: see how that is.

The NH is quite stable for a narrow boat, but it's not going to feel like the ES.