Photoshop enhancement of scanned picture

I have a scanned picture of an old magazine advert that needs enhancing to 300 dpi. A lot of it has already been done, so you can see what needs to be enhanced on the remainder. Basically, addressing faded colours, neatening low pixel edges and fixing colour bleed from the original print. I have dropped a before and after image in the samples. the entire image is 47408x35558 px. Only about 25% of the image needs working on now. I can share the whole image and run through requirements.