Reconditioning my 20yr old deck

I had to remove all decking on my deck to repair frame work issues as well has remove all rusted screws that had deteriorated over a course of 20 years. Deck was already built when I bought my house and never really gave it a thought until it just got too dangerous to walk on.

I had to replace 4 planks due to rot or extreme warping because the screws holding the planks were gone. I’m ready to pressure wash and brighten the deck then apply a sealer.

My question is, is it ok to flip the boards to reveal the better less weathered side? Or stick with the original side and brush and wash it. Is there a way to remove the marks from the joists on the flip side? Also what would be the best way to blend the new wood with the old wood so they don’t look out of place? I know I won’t get it perfectly blended, just wonder what’s the best practice is in this situation.

I have included photos one showing the planks flipped with new boards and one showing the extent of the weathering I am dealing with on the old boards. I’m ready to fasten the planks down with new screws and just don’t know how I should proceed with the planks - flip em or no?

Any advice would be greatly appreciated

Thanks!