How cold is it?
Don't shoot me here guys, but if it is really cold how about cutting the viscosity down with a little diesel (or fluid that has lube qualities) or something. That may help your valve until spring when you can drain it and put a valve in it.
Many old tractors recommended cutting fluids when it was very cold but I have not heard whether this was a practice for Fords with a common sump.
I'd do something to help that sticking valve until spring when it was warmer.