WWII Enfields were finished by a process know as oil blackening....
Post war refurbs, the guns were actually painted using a paint called "Suncorite"....
So you could use a good, high temp engine or bar-b-q type paint. I have had success with this in the past. This was on a jungle carbine that was basically in the white....I typically don't do this!
I used a good, high temp engine paint. After I thoroughly cleaned and degreased the metal with acetone, I sprayed it using light coats, letting it dry for a little between coats. Then I let it dry pretty well for an hour or two, then buffed it with a soft cotton cloth.
The result really looked like a smooth, oil blackened finish. It was pretty much perfect.
But I would suggest using some 0000 steel wool and Hoppes on the rust. Do the whole gun, and if there is still finish left, leave it. Collector value really suffers when things are re-finished....