Well you have cold solder joins for sure that need to be fixed. That is from the first picture you posted of the bottom of a display board. Top right looks like it needs a reflow to me. I would do the same check on every board you have in there to be honest.
Both of those capacitors need to be replaced for sure. Those both look original. The fuse clips look ok, but I would replace those too and drop a new fuse in.
These are the resistors i was talking about (I'm pretty sure at least, I would need to double check later to be sure, but you can look it up as well, its a common thing mentioned to do to these boards) and yours don't look too bad. They are a little darker but not horribly so, so you'd probably be fine for now. Mine were boarder-line black and had shaded the board around them a few shades darker as well from the heat.
Beyond what I mentioned above, you probably will want to replace the headers on the Display boards and the SDB along with repinning the connectors. Remember to use the trifurcon connectors (not sure I spelled that right) when you can as they are the better replacement. All the parts to do that will not cost much as they are all fairly standard items. You can reference the rebuild guide that @vid1900 made for the SDB as well https://pinside.com/pinball/forum/topic/vids-guide-quick-bally-driver-board-repair-bulletproofing
That is the guide I followed when I rebuild my SDB board and it has worked perfectly since then.