Keep in mind that you are asking on a S&W Collectors forum. But it's your gun ,and there is no outcry of OMG , leave it alone. What you have is probably as close to a generic shooter as a pre-war long acton K frames gets. And as noted whatever you do will be for your personal satisfaction .

The absolute cheapest route is to deal with the rust as well as you can , and use professional grade cold blue. I personally feel that Brownell's T-4 give better more even color than the 5% more durable Oxpho Blue.

If you want somthing vaguely period correct for it's origional configuration a bead blast blueing would give a coverup for the rust damage.

If I were to instead more generally evoke the a period correct-ish encarnation of a pre-war long action generally , I would go with Nickle. Just because I like them , but it was a popular finish in the day.