Is there an easy way to degrease and de rust a K frame?

Yeah, there is no ''easy'' way.
What I do is to scrape all of the gunk off and clean what I can see with solvent and/or oven cleaner.
Then I wire wheel it all with a angle grinder.
I heat up the seams with a torch and I weld all of them solid.
For the shitty factory welds on the mounts etc. I grind them down and mig them so they are stronger than ever produced.
I add reinforcements around the steering box, the lower strut rod mounting points, and weld a big washer to the ends where the torsion bars go through.
Then I paint it with Tremclad gloss black spray bombs in and out, (that **** is amazing) and call her good.
The factory never put any where near this detail when new or close to it, so anything you do will be a bonus.

Actually, in the real world, there's no use in over thinking this.....a good clean up with some rust resistant paint is good enough unless you are autocrossing or drag racing the car....