I work for an equipment dealer, and we just dealt with this here in middle Tennessee a couple of months ago.
You need to drain the engine ASAP. Depending on how high the water level you got, you could have water in the cylinders and that will sieze the engine up in a hurry. It wouldn't hurt at all to pull the spark plugs and pour some oil into the cylinders, either.
Otherwise, drain your fluids, flush with whatever type fluid you drained, then refill. Plan on having your generator and starter rebuilt. The N series Fords did not have many electrical connectors that will retain water, unlike modern equipment with multiple wires inside a plastic plug. Pull the distributor cap and let it dry out/ spray it with something to dry it out. If the battery was hooked up while it was submerged, the water may have caused a short and damaged your points and condensor.
My biggest concern would be water sitting in the cylinders. The good news is, worst case scenario the 8N is still a common tractor, and engine rebuild kits are available. If you get it drained soon you probably won't have to go that far, but at least if you do, it's a simple tractor to work on with good parts availability.