You know, I'll be honest, I haven't revisited most of Conway's second stretch on the Spider-Man books in years. But those years are burned into my memory in a good way.
The JJJ/Chameleon story was a real standout. It was almost undeniably the best JJJ story ever written until "Under the Moustache," and there's still a case to be made for it.
The Tombstone/Robbie stuff was fantastic, edge of your seat drama. But don't forget Glory Grant and the Lobos Brothers! And some very cool one offs featuring the Punisher (and a villain called the Persuader), or John Walker Cap and the Tarantula.
But if you want a quick way to see how much Conway improved as a writer, check out the Carrion story from TSSM 149: