Both should be inspected corrosive glue used to hold some caps down (can absorb moisture and short things out over the years), and bad solder joints retouched with fresh solder. This is especially wise on the "Class A" area of the B-2x power amp boards which have a series of TO-220 transistors which run very hot. It's good to clean and redo the thermal paste at the same time.
Unfortunately it's not a quick or small job, it's either quite time consuming, or a little expensive for someone to do the job properly - however it would be well worth it for those excellent and valuable pieces you've purchased. While there's always a risk of failure if the pieces are used unrestored, if they were sold as functioning, maybe it's not a bad idea to take the small risk (if you're comfortable with that) and listen to them first to decide if you can justify the time / expense in restoring them. Once restored (correctly, by the right person) they will easily endure another 30+ years of regular use.
If you ask anyone here I'm sure they'll agree those pieces are certainly worth it.
Searching and reading through this forum will give you most information you need, if you wish to tackle the project yourself. The important tool you'll need in that case is patience.
A nice gallery here of a restored one:
https://www.flickr.com/photos/77313494@N03/sets/72157633401219486
Welcome to AK and congratulations on your purchase!