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

I painted the K frame with glossy black Rustoleum. I know that is not the highest quality paint but I am tired of paying shipping charges for every thing. The ends with the holes for the control arms are impossible to get a brush into the inside. I closed up the openings with wads of aluminum foil and poured the Rustoleum into the K frame and swished it around, then poured it out into a paint tray. The rest of the inside I was able to get with a sponge brush and a throwaway brush. I will brush on a second coat on the outside. At the factory, these parts were dipped in paint probably the same quality as Rustoleum. That is good enough as this car is retired from daily driving in winter salt.
Thank you for the complement, Harrisonm. I am also restoring a 1940 Lasalle. I know a lot more about Lasalles. I often help new owners on the Cadillac and Lasalle Club website forum and I appreciate the follow ups also.