The Suntour 7 GT isn't really compatible with Accushift since it only has a lower pivot spring, all Accushift rd have an upper and lower pivot. The 6 speed Accushift will work with the Shimano freewheels since the spacing between the cogs is very close to that of the Suntour Accushift freewheels. The spacing of the 7speed freewheels aren't that close between Suntour and Shimano. And of course, the Suntour 7 GT will work fine with the shifters in "friction" mode, but you knew that.