Window post/framing wood type?

I need to replace the wood framing around the frosted glass window that is located right next to the front door. The horizontal "mutton", as I believe are called on traditional windows, along the ground is rotted. The piece between the vertical post and door jamb. My question is what type of wood to use. I am guessing the original beams and posts in Eichler homes are Redwood or Douglas Fur.

Appreciate insights. Of course I am not going to be slavish to originality here as it will be painted. It will be cut to match the original size. I could use man made woods or other more water resisitant woods. The repairs will be primed and painted to ensure a good seal, so I am fine with wood.

Thanks, Nelson