Help Needed With Restoration Of Photos...

OK, so the reason I purchased Photoshop/Lightroom and invested in an expensive new computer to run it was because I am in the process of pubblishing a large size photo book of a UK Droog-Punk band from 1980-1982. After a near 40 year quest to get hold of a set of photos used on the bands first 7'' single I finally got hold of the negatives a few months ago. My initail joy at finally getting them in my posession soon drained out of me when I got the scans back from a professional film scanning company. It seems that many of the negatives were damaged, like some sort of liquid has been spilt on them in the past. My first thought was to get all the negatives professionaly cleaned with chemicals to see if that restores the negatives, however there dosent seem to be anywhere in the UK that does it.

So I started the process of trying to fix the photos myself in Lightroom. I Already expected that I would need to remove spots or a few imperfections even scratches etc and to be honest I've got quite a few looking superb but some of the repair work on others is beyond my limited ability using Lightroom/Photoshop. So my question is can photos like the one I've included be 'fixed' in Photoshop to make them look perfect and remove all the staining/imperfections so they can be used in my book???

In particular its the faces I'm having trouble with. If you look at the photo I have included the two fellas on the right their faces are damaged, can these be fixed? I Have tried to fix them using the AI tool but its really hit and miss and most of the time dosent like right. You can also see a lot of staining on the right side. If you were to divide the photo into four quarters then the bottom left quarter is ok, the other three have some sort of imperfections on them.

Does anyone have any advice on how to fix photos like this (I have others which are much worse) or does anyone know of anyone who can do it for me, I would pay of course and use WeTransfer to send the scans as they are pretty high rez. This has stalled the book publication. I Already have a set of images bought from Getty Images and another set bought direct from the photographer and was planning on the book being printed this summer but its on hold now.

The picture I've included I've had to re-size to post on here but the original scans are high rez. Any help will be greatly appreaciated!