Staining Baltic Pine Floor Boards

I have 100 year old Baltic Pine Floorboards that have been polished previously. We are renovating the back half of the house and my wife is keen to change the boards. Unfortunately, l want to keep them as they flow through from the rest of the house.

We are now discussing the possibility of staining the boards a darker colour to give a new / modern feel to them.

The boards have dark spots on them in certain places. Is it possible to have the boards sanded down enough to get all marks out, and then stain them to a consistant colour (darker then they are now), rather than having light/dark tones through the wood?

Thanks
Reno