The original 1986's were red, they turned to blue near the end but they remained blue until 1997.
They produced a 320 in the 90s, not sure the first year of the 320, but 86 was not.
However, all the parts are interchangable and the motors bolt up so a newer 320 engine could fit on an 86 frame and a 320 top end might work on a 250 bottom end provided if the crank needed changed it was also changed.
I would say though that you'd just have to look at the cylinder and determine it yourself. At some point they switched to Nikasil like I said. In 86 though, they did not Nikasil.