The Sportour and the Miyata are essentially the same bike, same frame anyway, although (if we're talking mid-80s) the Sportour would be a step up because its fork is Mangalight instead of high-ten. Some came with Shimano 6000 derailleurs, some with Suntour Cyclone Mk II, both of which are nicer than the 310 spec. The Sportour will also have a 700c wheelset. I had a Sportour and loved it. I'd take it over the 310, all things being equal.