Lugged frame, cantis---it is a very nice bike, regardless, and definately a tourer. It looks a lot like my '83 610, and you got a steal at $160. What is the exact wording on the top tube, and what do the tubing stickers say?

The early 610's had the suicide levers, but not after mid-eighties, I think. Check out old Miyata catalogs at: http://www.miyatacatalogs.com/ . That site has info about serial numbers as well.

As far as upgrades, personally I would ditch the suicide levers and maybe get a wider handlebar (my old Sakae was ridiculously narrow). There are plenty of choices for good 27" tires these days (see that C&V thread), so you can keep the wheels if they are in good shape. Good luck!