DJ, all the yellow areas on the Saturn V was pristine. Aside from some oxidized areas on the exposed Stage One engine bells, everything about the craft was beautifully mainted on display. Not dirty at all. I’d suggest good old FS Insignia Yellow.
When my boys were littleish but old enough to have fun with ( now in mid latter 40’s) we built flying rockets. I used Krylon paint on them fwiw. I hear Krylon formulation has changed since those day but just thought I’d mention it.
Aside from a decal set, the kit was built without any aftermarket. The CSM and LM “garage” are undersized, but I just detailed the SM as best as I could and called it a day. The escape tower truss was refined but not corrected.