The front sprocket is significantly worn, not to mention ugly. I wouldn't run a new chain on it. The rear is in better shape. You could get by with it if you want to cheap out. It wouldn't hurt to clean it off. If you are going to ride the bike a lot, it might be best to replace the rear sprocket. If you ride it only a couple thousand miles a year, it'll last a good while.
Greg
'75 CB750F