Not too bad to work on. The motor has to come out for head work because it's a stressed member in the frame. It's not hard to get out once you get the nuts unstuck.
The camchain may be available from Honda, it's pretty basic. They are usually on ebay anyway. The tensioner is a big bakelite wheel, it might be damaged, I wonder why the owner has decided a new chain is required?
Of course it's an endless chain. I would rivet a replacement in.
The bottom end is pretty easy, the crank is on ball and roller bearings so there's no bearing shells to keep track of. You can not practically replace the centre crank bearing(s). You may know someone who can pull it apart and press it together again (this is another lost art) but the bearings will be a chore to find... and a used crank would probably be fine if yours has toasted bearings.
Problem areas? hmm. The points shaft goes through half the cam and if tt gets sloppy in its bushings then the spark timing gets unstable. The oil filter tends to be ignored, once it's full you don't have any filtering and things like that wear rather quickly.
The transmission shift forks wear on the tips, and can bend with brutal shifting - this gives you more than the stock number of neutrals plus slipping out of gear under power.
The primary chain breaks on occasion, usually without catastrophic damage (ie exploded cases). This is probably exacerbated by dirty oil as well, it's worth checking if you're in there and replacing if it's really worn out - they will gouge the cover when stretched. Unfortunately this is a weird chain and is unavailable new, you might find a used one less stretched out if yours is unusable though.
There are several excellent web sites on these bikes, and a lot of parts on ebay. Try to get parts from the same model year if you can, there were quite a few changes over the run. There's a fair bit of NOS stuff still around but the prices are nasty. You can get some repro parts but not as much as for a CB750.
