power coating is ok till it chips . moisture can get in and then the rust will build up under the coating.
enamel paint would do the same id guess.
rub it down and paint it with spray cans . that way if you decide to get it blued later its not going to need a lot to get it polished up.
there is the rust bluing that T20 did and documented on here. would only cost for the materials and your time.
there is Parkerizing too. like they did on army firearms . not sure on costs.
RichardH on here might be worth asking .