I like wood canvas canoes, and I admire your desire to use one for your planned NFCT thru paddle. I am presently helping a friend restore an OCTA and I think they are a fine canoe, unfortunately I have never paddled one.
Sometimes finding the right canoe at the right price when you need one can be a problem, especially if you want to use a wood canvas canoe.
If I was going to thru paddle the NFCT with a wood canvas canoe, I would use my 15' Chestnut Chum or have a 15' canoe built just for the trip, if I didn't have the Chum already.
Resupply on the NFCT is pretty easy from what I have gathered, you pass through towns and that is where you can resupply regularly. No need for heavy food packs, so no need for a big canoe. 16' is fine for a solo tripper (I used a 16' Chestnut Pal for many years solo), but my trips where never more than 2 weeks. I think your trip will be around 7 weeks, the OCTA will probably start out around 70-75lbs., and after some rain, depending on how much, it will gain some weight.
You have some pretty long portages on the trail, not all are wheel-able so that big heavy canoe could be a problem.
On the other hand, the OCTA at 16' would float high for poling upstream or going down bony streams and rivers, which could be a big plus. If aesthetics are of some importance, it would be a beauty out there on the trail.
If you think you could handle the weight from the get go, then maybe a water-proof canoe cover for those rainy days would help. I have used them, I made one from the floor of a worn out Timberline tent and it was great. Kept me warm, kept my gear dry, and most of all, kept the canoe dry and not water logged.
It made rainy days bearable.
Also, the condition of the canvas on the canoe is important. I would say it should be a fairly new canvas and I would pass on adding a keel, they are leak waiting to happen. I doubt if a keel would hold up for that long a trip without leakage and a serious weight gain. (imho)
A new canvas, some duct tape and some cain to repair the seat which will probably not hold up. A wood canvas canoe on the trail in good shape is nice, a wood canvas canoe with a duct taped seat half way thru sends the wrong message, again imho.